I'm part of the Vietnam War generation, so there is still a big question for me, and that is why Australia (and the other Commonweath countries) jumped uunquestioningly into both World Wars. There were in both wars some who questioned whether we should be involved, but they were regarded almost as traitors.
PM Menzies' statement in 1939 that "England has declared war on Germany. Australia is therefore also at war with Germany" has today been condemned by many legal experts as a load of rubbish: there was no legal requirement for Australia to follow England into war with Germany, or anybody else.
Only with Vietnam did Australians begin to question our blind obedience to foreign powers, and that came from the young, who were being asked to fight a war in a country we'd never heard of for a reason we didn't care about. Older Australians once again took it for granted that we would fight wherever we were asked to. Only when it dragged on with no victory and thousands of dead, did the older generations join the condemnation of that particular exercise in futility.
Yet there we were again this century, following the U.S. and the U.K. into a foreign war that not only had nothing to do with us, but was for obviously spurious reasons. Yet although hundreds of thousands marched in this country against it, once again, our craven politicians (most of whom had never been in any war), followed our foreign allies blindly into Iraq, and we are now all paying the price for the destabilisation of that country.
I feel pride and sadness for all the young men who "went with songs to the battle", having no idea of the horrors they were about to face, and who came back if they did come back wounded in mind and body. But it would have been better if they'd never gone.