German and British soldiers laid down their arms, and climbed out in to no man's land for an unofficial ceasefire during Christmas. Supposedly over 100,000 soldiers participated, gifts were exchanged, British soldiers cut the hair of German soldiers, officers swapped buttons and coats, privates exchanged candy - and the next day, the fighting resumed, and the carnage continued.
it's worth noting that not all parts of the front celebrated this truce, some parts of the frontline only had small agreements of a minor ceasefire to recover bodies, while others sang songs from within their trenches.