Martin Graebe wrote the song From Severn, By the Somme, which actually expresses the viewpoint of a man left behind, which I find quite moving. It's been recorded by Martyn Wyndham Read amongst others.

A CD which has a number of interesting songs based around this topic is another Coope Boyes and Simpson one, with the choir Wak Maar Proper "Christmas Truce/Kerstbestand" - I've probably spelled all that incorrectly!