Masters of War - Bob Dylan
And The Was Drags On - Donovan
Shipbuilding - Robert Wyatt / Elvis Costello
Fixin' To Die Rag - Country Joe & The Fish
No Doves Fly Here - The Mob
Major General Despair - Crass
Island of No Return &
The Price of Oil - both Billy Bragg
One Nation Under the Bomb - Conflict
Nagasaki Nightmare - Crass (again)
etc.
etc.
etc
Curtis Mayfield's "We've gotta have peace" is worth a listen. As is Emerson, Lake and Palmer's "Battlefield" from the album "Tarkus". Some great lyrics - "Clear the battlefield and let me see, all the profits from our victoree".
perhaps not for those of your era, but check out Flanders & Swann - 20 Tons of TNT. The maths are a little out these days (due to 50 years of progress) but still a powerful message.