Yes, anti-war songs have changed something: they have become an important aspect of a stereotype of anti-war protestors, making it easier for the authorities to categorise all anti-war protestors as beardy-weirdy folk singing Guardian reading idealists. Thus, the anti-war song makes anti-war protestors feel good about themselves, whilst making them an easier target for satire.

But that's more to do with style than content.

So, take the powerful, "Last Night Another Soldier" by the Angelic Upstarts... well, that helped to stereotype anti-war (peace in Northern Ireland) proetestors as scruffy thick anarchist punks... an easy target for satire.

Songs don't change the world. They do, however, act as a bonding agent for groups of people who might change the world, but probably won't.