Warning. This is a doozy. And by doozy I mean more than 2500 words.

It's so long, in fact, that Reddit won't let me post it all in one comment, so I've broken this into two parts. The first part is here. The second part is as a comment to this. If anyone would like to comment or ask follow up questions, please do so on Part II below.

Part I

I’ll speak to the open and transitionary phase of warfare on the Western Front in 1914. I could discuss 1918 as well, but this answer will be long enough. Needless to say, a comparative approach like that would be interesting, but I simply don’t have the time to tackle it.

If you’re interested in 1918, I recommend looking at the Battle of Amiens. There, we have a British Army employing advanced combined arms tactics to good effect, the result of four years of learning and grinding in the West.

The first couple months were very different.

In terms of structure, I think I’ll briefly look at how these armies expected and planned to fight in 1914. Then I’ll look at the following engagements: the early fighting in Alsace, the Ardennes, the Battle of the Marne, and finally the Race to the Sea and quickly the First Battle of Ypres.

At the end, I’ll identify four common themes I think answer your question most directly: communications, absence of artillery support, fighting in villages, farms, etc., and casualties. I’ll highlight these as I go through my examinations of my chosen engagements.

I’ve relied heavily on Holger Herwig’s The Marne, which I highly recommend if you’re interested in the open phase of the war.

Prewar Tactics

I see lots of readers, particularly on this subreddit, who believe that armies went to war in 1914 with “Napoleonic” tactics. That’s an oversimplification. While it’s true that armies didn’t have effective combined arms systems like they did in 1918, tactics still attempted to make the best of improved firepower in the form of quick-firing artillery, magazine-fed rifles, and water-cooled machine guns.

All armies in the West believed that the offensive was key to victory. To pass the initiative to the enemy was certain to result in defeat. Striking quickly and boldly thus formed the backbone of tactical systems before the war.

In regards artillery, the French army and, to a somewhat lesser extent, the British army favored close infantry support. Their pieces were mostly field guns designed to be wheeled into battle and fire on targets directly. They had few howitzers that could be dug in safely behind the firing line. The Germans, because they had to reduce the fortress complexes in France and Belgium, had heavier guns and more howitzers, but indirect firing remained in its infancy in 1914. Everyone paid lip service to the importance of coordinating infantry and artillery, but no one really figured out how best to do it. Setting up guns in the firing line with the infantry remained the go-to plan.

Infantry tactics generally emphasized a decisive attack, often with the bayonet. In essence, you’d engage the enemy in a firefight, attempt to draw in his reserves, and then launch a general counterattack at a flank or weak point in the line. The final bayonet charge was meant to break the enemy’s morale, instigating a retreat. As will become apparent from below, such a neat system rarely played out in practice, due largely to poor communications.

I’ve oversimplified somewhat here for economy’s sake, but it’s important to note that nobody assumed that this type of fighting would be bloodless. All armies recognized the deadly nature of new weapons and expected heavy losses.

Finally, I’d like to emphasize that all sides were prepared to dig. The British Army, for example, had clear plans for deploying entrenchments in conjunction with the system of fighting I’ve described above. So did the Germans, and so did the French. Trenches, though, were a means to an end. Field fortifications were meant to strengthen the line so that armies could bolster their reserves, thereby giving more weight to their counterattacking forces. As soon as armies started colliding in 1914, they took to the spade.

Alsace-Lorraine

For this section, I’ll take a look at the fighting in and around Mulhouse in Alsace. As part of its war plan (Plan XVII), the French pushed into Alsace-Lorraine. The plan was to “fix” the German left wing, but there was an obviously nationalistic agenda in the plan.

On August 7, French VII Corps under Bonneau (who was Alsatian-born) advanced toward Altkirch and pushed out the small German garrison at the point of the bayonet. He took Mulhouse without opposition the next day. The Germans moved against Mulhouse on August 9, but the attack quickly degenerated into disorderly frontal assaults. The area was heavily wooded and had many vineyards, so the fighting was in close quarters.

Casualties were heavy. According to Herwig, at Napoleon Island on the Rhone-Rhine Canal, French defenders on raised platforms fired at German troops coming through grain fields, inflicting “severe losses.” Confusion at the battalion and regiment level was endemic. Units didn’t receive orders or lost them, and some commanders refused to launch frontal attacks when ordered. The Germans managed to retake Mulhouse, but it was a bloody affair.

So to sum up Mulhouse as my example from Alsace-Lorraine, we see a back-and-forth fight in woods, vineyards, and populated areas. The fighting was chaotic, and costly frontal assaults were commonplace.

The Ardennes

Here, I’ll look at one specific case to demonstrate the nature of the fighting. Like we see in Alsace, fighting was confused and chaotic, and infantry often charged with little or no artillery support.

In mid-August, it was becoming more apparent to the French high command that the German right wing was disproportionally strong. French Fifth Army, under Lanrezac, moved up to counter German Second Army along the Sambre River on August 20. Initially, both sides were cautious. The British were en route, so the French toyed with waiting and advancing with allies on their left. Bulow, commander of German Second Army, wanted to maintain contact with the forces on his left and right, so he, too, was initially cautious. But by August 22, though, he was ready to attack, which he did with three corps.

The French, however, were also attacking. Two of Lanrezac’s corps commanders (those of III and X Corps) attacked without orders, and the subsequent fighting was a classic encounter battle: both sides simultaneously advancing against one another. I’ll quote Herwig’s description of the French advance. As you read this, keep in mind that the French troops wore bright red pants and blue tunics.

Without orders, Sauret and Defforges [the French corps commanders who attacked without orders] charged the German positions in the early-hour mists of 22 August, flags unfurled, bugles blaring, bayonets fixed---and without artillery support. Both attacks were brutally beaten back around Arsimons with “staggering losses.” Tenth Corps’ desperate bayonet charges were mowed down by the machine guns of the Prussian Guard; those of III Corps ran headlong into a fierce assault by Emmlich’s [German] X Corps. The fields were littered with six thousand French dead and wounded; the roads were soon clogged with thousands of Belgian civilians fleeing the deadly mayhem.

We can see here the problem and command and control rearing its ugly head again. Corps commanders attacked without official orders, and Lanrezac could do little about it. Keeping in touch with subordinate formations was difficult and often done via runners, not telephone. At the tactical level, units did not have radios linking them to artillery units further back. Battalions would get intermingled with one another and the whole scene would devolve into chaotic frontal assaults.