For one thing, the Christmas truce was not observed universally across the Western Front. According to the Imperial War Museum, the nature of trench warfare in 1914 was that each sector was quite distinct; if one sector of trenches was observing a truce, or vice versa, neighboring sectors may not have had a clue.

So although a truce was indeed observed in many sectors along the front in Belgium and France on Christmas Day 1914, this wasn’t true across the entire front line. Some soldiers — understandably — felt no desire to socialize with the enemy. In a few places, soldiers were ordered to fire on their unarmed counterparts.

But in other sectors, the young men who had days before been firing upon each other found that their enemy was surprisingly relatable. According to one account, the men on both sides of the trenches began singing carols on Christmas Eve — their hoarse voices, singing in their respective native tongues, carrying over the pockmarked ground. Then, according to the witness, a German soldier shouted across the 30-yard expanse: “Tomorrow, you no shoot, we no shoot.”

The next morning, after crossing into no man’s land, the young soldiers began exchanging chocolate, alcohol, and cigarettes. A soccer ball was produced, which led to a hearty, informal “kickabout.” After hours of socializing and enjoying each other’s company — and also burying and paying respects to their dead — the men from both sides returned to their trenches, unharmed.

The Christmas truce didn’t come out of nowhere. The pope at the time, Benedict XV, had often decried the aggression and bloodshed of the war and had most recently called for peace in a letter a few weeks before Christmas 1914. (He also reportedly asked, in explicit terms, for a Christmas truce, though the primary source for this request proved difficult to find.) Though ignored by the leaders of the armies — and perhaps unknown to many of the soldiers — by divine providence, the truce for which Benedict pleaded ultimately came to pass.

Photography was discouraged in the trenches, but many photos were taken anyway, especially during the truce. Thanks to those photos and the written accounts of the soldiers in their letters and diaries, newspapers the world over began to publish accounts of the truce at the end of December 1914, adding to the event’s authenticity.

Though imprinted on the memories of the men who took part in it, it is difficult to say whether the truce did anything to change the course of the war. Moreover, truces in general became much more rare after 1914, after strict orders from high commanders on both sides warning against future truces. Fraternizing with the enemy was incredibly risky, and commanders cracked down on it, amid aggressive propaganda campaigns on both sides to dehumanize — and instill hatred for — the enemy.

The orders may have been moot, though, because the war itself began to change — while certainly brutal before, conditions and tactics became even more cruel as the war went on, especially on the German side, with new and deadly methods such as gas and tank warfare starting to be employed. German submarine activity led to the sinking of ships like the Lusitania, with massive civilian casualties. On the whole, the temptation to empathize with the enemy faded away in the trenches.

Partly as a result of this, the Christmas truce, despite being well-documented, took on a mythic character. It certainly happened — but nothing as widespread ever came close to happening again.

The “Great War,” of course, came to an end a few years later, in November 1918. But strife, conflict, and sectarian violence continues today. Constant calls for ceasefires continue in places like Ukraine, with Pope Francis often a leading voice.

The hope that this episode from history instills — the hope that on the day that the Prince of Peace was born, peace could reign on earth — is irresistible. Perhaps, this year, we might see something like the Christmas truce happen once again.