One of the stories that emerged from the event was that, in the quiet of Christmas Eve night, some young German started singing "Stille Nacht". Soon the British, French and Scots on the other side of No Man's Land (oftentimes measuring only a hundred yards wide) joined in in their own tongues. Before long, the spirit of peace and "goodwill towards men" prevailed over the demonic spirit of war, and the troops on both sides sensed their common humanity. The natural human aversion to killing broke through to consciousness and overcame the patriotic fervor and brain-washing to which they had been subjected.
Once the spirit of peace was felt, soldiers on both sides dropped their weapons and came out of their trenches to meet their former foes face-to-face. To get through to the other side they had to step around shell holes and over frozen corpses (which were soon given respectful burials, soldiers from both sides helping one another with the gruesome task).
The spirit of retaliation had dissipated and the desire for peace on earth emerged. New friends shared chocolate bars, cigarettes, beer, wine, schnapps, soccer games and pictures from home. Addresses were exchanged, photos were taken and every soldier who genuinely experienced the emotional drama was forever changed - and the generals and the gung-ho politicians were appalled.
Then the boys went back to fighting for another 4 years, in the War to End All Wars (how did that work out?).
My great-grandfather, a German soldier, in all likelihood was not present for this truce. He was killed on the last day of the war in 1918, so the odds of him having been a part of the truce, and surviving the next 4 years, would have been astronomical. I've posted that family story here.