The Christmas Truce of 1914.
BBC magazine provides a lot of detail in its article about the French attitudes about the truce. Surprisingly, so does the Washington Post. I had not expected to see anything in the US media since America was not involved. The Post story links to a photo archive of the event. In some of the photos I cannot distinguish between the two sides, a testament to their shared humanity.
"...on each end of the rifle we're the same."