It was common enough for there to have been hundreds of thousands of men who did it. But it wasn't common enough to have been the norm.

Let's look at the British Army in 1914. There were just under 250,000 men in the regular British Army and just over 200,000 men in the Territorial Army and other reserve formations when Britain entered the war in August 1914. Now, not all of these men were frontline soldiers. The British Army had a far larger tooth-to-tail ratio than it does today, but there were still tens of thousands of men in support units like the Royal Army Service Corps. Furthermore, not all of these men were immediately deployable. About half of the regular army was in overseas garrisons like India. So there weren't that many men able to fight in 1914 for the British (France, Germany, and Russia are a little bit of a different story, since they had large armies composed mostly of reservists, so they were able to field large armies from the onset of the war).

As a result, the initial British Expeditionary Force sent to fight in France and Belgium in August 1914 was only around 90,000 men. Now, this would soon swell to 150,000 men when it was reinforced with two additional divisions. And by the end of 1914, it was nearly double its original size, since divisions from the Territorial Army and the British Indian Army had been moved to strengthen the BEF. But by the end of 1914, many of the original BEF was gone. In 1914, the BEF had taken 90,000 casualties.

And these casualties had fallen disproportionately on the infantry regiments thrown into the meatgrinder of places like Mons and Le Cateau. In one day at the Battle of Mons (August 23, 1914), the 4th Battalion, Middlesex Regiment lost 15 officers (5 KIA, 10 WIA and/or POW), 253 other ranks (90 KIA) and had only 375 men fit to fight.

Although popular media tends to focus on the trench battles of subsequent years, 1914 actually saw the bloodiest days of the war. There were over 19,000 British and Commonwealth dead on July 1, 1916 on the Somme. By contrast, France lost 27,000 dead on August 22nd, 1914, and that was just one day of the Battle of the Frontiers. In the August 1914 Battle of the Frontiers, there were 400,000 casualties on both sides, followed by another 500,000 to 600,000 in the Battle of the Marne, fought over less than a week during early September 1914. In those cases, most of the dead were killed in attacks over open ground when they were hit by artillery. Machine guns and rifles also caused quite a few losses, but artillery was by far the biggest killer during 1914.

Your odds of surviving 1914 as a rifleman were not good, at least on the Western Front.

And your odds of surviving the war unhurt weren't good either. Fifty-five percent*of the British Army who served on the Western Front became a casualty (killed, wounded, or captured).

*I don't know if this figure accounts for men who died of disease or were invalided out due to wounds or shell shock.

But remember, that's the figure for the total army. Unsurprisingly, those losses fell proportionality on combat troops. About 85 percent of casualties were suffered in the infantry, about 10 percent by other combat troops like artillerymen, and supporting troops suffered the remaining five percent. When you do the math, a British infantryman had about a 120% chance of becoming a casualty. Now, some wounded men would have been able to return to service, so becoming a casualty isn't an automatic "for you the war is over" ticket. However, about one in five infantry casualties died.

If you look at the figures for the 1st Battalion, Grenadier Guards, which first reached the front in October 1914, thereby missing some of the bloodiest months of 1914. Even with this small mercy, they still lost 1,286 men dead to all causes (disease, accidents, enemy action) during the war. All in all, 4,434 men would serve with 1st Battalion during the war. Given that a battalion had a paper strength of about 1,000 men, that's a turnover rate of over four hundred percent! Obviously some of these men transferred to other units, were invalided home, or were captured. But many were not so lucky. Most men who got out of infantry battalions during the war left on a stretcher or in a coffin. In all of the battalions of the Grenadier Guards, three out of every ten Guardsmen who served would die during the war.

However, service on the front lines was not an automatic death sentence. About 145,000 British soldiers received the 1914 Star with Clasp. This medal was given after the war to applicants who could prove they had served within range of German field artillery in France or Belgium between 5 August and 22 November 1914, the hottest period of fighting for the BEF in 1914. Anecdotally at least, we know some of the men who were awarded this medal were still serving in combat units when the war ended. Anecdotally, we also know many of these long-serving veterans had been wounded at least once by the war's end.

There were survivors in other armies as well, of course. Two of the war's best-known soldier-authors were 1914-1918 veterans. French diarist Louis Barthas and German stormtrooper Ernst Jünger both served the entire war on the front lines (although Jünger took stints away from combat for convalescence and training).