Today is the 99th anniversary of the Christmas Truce of 1914, a spontaneous soldiers’ truce that broke out on Christmas Eve all along the Western Front in France, lasting in places until the day after Christmas.

French, British and German soldiers, intrigued by the sound of Christmas carols from the enemy trenches, first tentatively refrained from firing on one another. A German boot tossed into the British trenches turned out to be filled with candy and sausage. Soldiers, with increasing confidence, began to venture out into no-man’s land and into each other’s trenches to exchange small presents like coffee and cigarettes, spirits, and newspapers from home. They celebrated Christmas by playing football on no-man’s-land. Soldiers from opposing armies shared rations, sang carols together and posed for group photographs.

The Allies and Central Powers had previously called temporary truces as Christmas approached, in order to bury their dead — but only with approval from their respective High Commands. This Christmas truce, in contrast, was completely unauthorized by commanders on either side, a violation of discipline in just about every imaginable respect (fraternization with the enemy — a court-martialable offense — just for starters). And needless to say, the German and Allied leaderships were utterly terrified by the implications — even more terrified than after the Armistice in 1918 when a British unit in France, impatient for demobilization, organized a soviet. They racked their brains to come up with a way to threaten or trick the men in the trenches into ending the unauthorized truce and getting back to killing one another.

The soldiers weren’t having any of it, though. Directly ordered to resume fire on December 26, they perfunctorily fired their rifles into the air rather than at the enemy. Finally the High Commands ended the truce by bringing in fresh troops from the rear who had not experienced the truce. In Christmas 1915 and subsequent years, truces were prevented by ordering continuous artillery barrages from the rear, and making conspicuous examples of officers who even hinted at allowing another Christmas truce. A British captain who authorized a local truce for burying the dead, followed by half an hour of fraternization, was court-martialed.

The governments and military commands of Britain, France and Germany were rightly afraid of this development. It was fairly easy to demonize the enemy to the civilian population at home with official war propaganda, like the stories in the British press about German soldiers bayoneting Belgian infants. But soldiers who came into direct contact with the “enemy” on the front quickly learned that they were just regular people like themselves with jobs and families at home, who had been stupid enough to believe the lies their politicians had told them.

Today our rulers have much more reason to be afraid. Since the rise of the Internet and near-ubiquitous connectivity in much of the world, and the rapid growth of social media networks, there’s been at the very least an order of magnitude increase in the number of Americans who have direct person-to-person communications with citizens of “enemy” nations whenever the United States goes to war. And we have not only easy access to media outlets like Al Jazeera showing the charred and dismembered bodies from U.S. air strikes, but ordinary people uploading images or videos to social media via cell phone.

It took a physical trip into the opposing trenches ninety-nine years ago for soldiers to discover that “enemy” troops were just like them, and their real enemies were back home in London, Paris and Berlin. Today a large, and rapidly growing, portion of the civilian public knows that before a shot is ever fired.