Sorry, I've started looking at this thread quite late ...

About WWI (above), I don't think it's too surprising that there is no sign of popular war-oriented songs.

These are US charts and the USA was not involved in WWI at all until April 1917. Even after that, there was no really significant battlefield presence by US forces until the spring of 1918, so they were only really there for 6 months.

Total US troop deaths in WWI, by the way, amounted to 110,000 of which 43,000 were due to the flu epidemic (this killed 675,000 people in the USA during 1918/19).

There don't seem to be any songs about that either.

Ian