Georgina above has it right. According to Christmas Truce by Malcolm Brown and Shirley Seaton, there were dozens of localized Christmas truces in 1914 but only two or three in 1915. The British command gave explicit orders in 1915 that any fraternizing would be severely punished and that any German above the parapet should be shot. One company commander (Capt. Sir Iain Colquhoun of the 1/Scots Guards) got into big trouble for allowing half an hour for the Germans and Brits to bury the dead bodies lying in No Man's Land.

The Christmas truce of 1914 is an inspiring story and is very well told in the book Christmas Truce.

David