Truce: The Day The Soldiers Stopped Fighting by Jim Murphy

It was a truce called by the soldiers themselves at Christmas on December 25, 1914.  Amidst the slaughter and filth that was trench warfare during WWI, British and German soldiers themselves halted the war so that each could celebrate peace on earth and good will to men for one special day.

Also recommended: Silent Night: The Story of the World War I Christmas Truce by Stanley Weintraub