Grace,

I'm assuming British Army Am I right in assuming that by "early war" (and from your comment about ending with a Christmas Truce song[1]), you mean pre-December 1914? If so, you are better off with music hall songs ("It's a Long, Long Way to Tipperary", "Who Were You With Last Night?", "Hello! Hello! Who's Your Lady Friend?", "Hold Your Hand Out, Naughty Boy", "Hitchy Koo" etc.) or, as a war usually start using the songs of the last one (or thereabouts), the odd Boer War tune (including some of the Boer ones) otherwise you may have to be more specific (there were an awful number of songs which had become, almost, regiment specific), otherwise, you could try "Never Trust a Sailor" [Don't Never Trust a Sailor?] or "Christmas Day in the Workhouse"

Regards

Walrus

[1] btw, the truce was Christmas Day, not Eve (and in some sectors, for several days later).