My mother, who was born in 1917, would sing a song from The Great War, "Good bye ma, good bye Pa, good bye mule with your old Hee Haw, and fare you well my sweet heart dear, I'll bring you a king for a souvenir. I'll bring you a king and a kaiser too, and that's about all one feller can do."
There's another ditty from that era called the "Indianola" that ends with, "Me just love to kill, gonna go and scalpum Kaiser Bill."

For some reason I always sang "Rally Round the Flag Boys", when driving home from Howard Dean meetups. It's from an older war, but it still suggests fighting is a good idea.

Hollowfox and I were serenading two reenactors, who do the 42nd Highlanders in the French and Indian war with "Twa Recruiting Sergeants".