On the Vintage Ads LiveJournal, a fascinating set of anti-war ads from the 1930s protest group World Peaceways (see the full-sized version to read the text). They ran an anti-imperialist anti-war campaign that described soldiers as pawns in the corrupt games of the rich and powerful, and called on everyday people to refuse to involve America in future wars.
World Peaceways (1930s pacifist/anti-war organization) produced some of the boldest propaganda posters of that era, largely aimed at looking at what had come about in the aftermath of the First World War, including the Depression, and death on a scale the world had not seen before, as well as lasting enmity that was quickly brewing into the Second World War.
The name "World Peaceways" was used in the famous Star Trek episode "City on the Edge of Forever" to represent the pacifist movement that Edith Keeler belonged to. The story claimed that her peace work would keep America out of the war for too long and thus lead to Germany winning and taking over the United States. Kirk HAD to let her die - because if he saved her (as he apparently had) then all of history would change.