I've answered similar questions before so I'll paraphrase those for you.

Basically, the construction of trench systems was not planned, at least initially. The nature of the type of warfare faced by the infantry during the First World War saw most seek shelter wherever they could to get away from machine guns and artillery. Neither side was willing to withdraw out of range and concede ground to the enemy so the safest place to be was below ground level. Trench systems often began as individual holes dug hurriedly by soldiers for protection from bullets and shell fire or as shell holes which served to offer protection.

As moving about above ground was extremely dangerous, soldiers expanded their limited shelter and connected them together, eventually forming interconnected systems that would become trenches. As time wore on and the frontline didn't move, soldiers would work on their trenches, improving them, digging dugouts, communication trenches to connect to trench lines further back, they reinforced and deepened their positions and made them more accomodating.

Allied trench systems were seldom of better quality then their German enemy as the Allies considered the the stalemate on the Western Front to be a temporary state of affairs and future offensives would see the trench systems abandoned as the frontline shifted. The Germans on the other hand were happy to maintain a defensive stance on the Western Front whilst the dealt with the Russian threat in their East. As a consequence to this, German trench systems were far more elaborate, better constructed and reinforced in order to offer a far more formidable obstacle to attacking Allied armies.

A trench is a defence: armies have been using fieldworks to protect themselves for centuries. The benefit of the trench is that it allows relatively quick movement while still concealing much of the soldier's body from enemy fire, and limiting injury to attacks that come directly from above: the biggest cause of death in the First World War was artillery fire, from airbursting shrapnel shells that could rain fragmentation down into the trenches. This was why armies adopted steel helmets.

Most armies then and now accept that a pause of any length in an advance should be accompanied by digging in, first as shell scrapes, then as more developed trenches. The trenches of the First World War largely grew out of this: after the Germans were halted at the First Battle of the Marne in 1914, they withdrew to more defensible positions on high ground overlooking the River Aisne and dug in, where they received the British and French counteroffensive. After the Entente proved unable to break through German lines on the Aisne, they began a series of outflanking attempts to the north, which largely foundered against German defences, and which became known as the "Race to the Sea" after it ended at the First Battle of Ypres near the Belgian coast. The deep, elaborate trench systems of the First World War largely grew out of these first defences established in the summer and autumn of 1914.

As for how they became so deep and elaborate, work to improve the trenches was largely done at night. Corrugated iron was used to revet the trenches, while wiring parties were sent into No Man's Land under cover of darkness to establish barbed wire obstacles. These were initially strung onto wooden posts hammered into the ground, but as this tended to attract enemy fire, they were replaced by iron pickets that could be screwed silently into the ground.

As for whether there was mutual agreement between the two sides, I cannot speak for that. There were certainly periods throughout the war where soldiers in opposing trenches adopted a "live and let live" attitude towards each other, but whether this extended to ignoring wiring parties moving into No Man's Land I cannot say.

Sources:

Gordon Corrigan, Mud, Blood and Poppycock

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting.

B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it.

Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting.

B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it.

Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting.

B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it.

Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost-effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which was too dangerous to build during those times. Trenches often provide a safe space for a sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing was fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights were already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situation, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides have a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost-effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which was too dangerous to build during those times. Trenches often provide a safe space for a sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing was fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights were already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situation, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides have a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

I wanna comment, but reddit's being a bitch

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.

A: Cost effectiveness, it was better to use natural terrains than using up resources like sandbags and wood. They require constant maintenance which were too dangerous to build during those times. Trenches often provide a safe space for sniper to operate and really: the only place you can be shot is your head. But you got a helmet and you can just keep your head down, and since grenades are harder to throw: it’s hard that it would actually land in the trenches and hit someone with a fragment than if it were thrown at a fort defense. Yes: mortars were used. But it was hard to calculate where they were landing since: Their hearing were fucked up from all the gunfire’s and explosions It was hard to peek where it actually landed There were overhead covers as well, and firing at it were simply not worth the targeting. B: Ha! Reading that actually made me laugh a little, not because it was ‘stupid’ but it’s because I used to wonder the same thing as well. No, they didn’t have “truces” to dig the trenches. They were built at night at the cover of darkness. Yes, spotlights was already invented but they needed electric power and there were simply no rooms for generators. The diggers were in a very dangerous situations, random shots could hit them and any time but they were ordered by their sergeant to dig. Germans actually lived better trench lives than the French and British. This was because before the war, they had time advantage before they arrived to dig better for bunkers, many soldiers on the Allied side died of infections and diseases as gun deaths. If you want to talk about the agreement tho: you can talk about the Christmas Truce. Summarizing: the two sides has a temporary illegal ceasefire during Christmas Day and embraced each other. Young soldiers who lost all cause for living returned to their boyhood for one day and simply played together as one. I recommend looking up about it. Hope this helped! PS: This is all from my memory, APWH really scars you.