Vietnam War

Public Reason
Australia is asked by the South Vietnamese government for assistance and then consults with America about the decision to send troops.

Real Reason Australia went to Vietnam
Papua New Guinea was split into two countries - West New Guinea (Netherlands) and New Guinea (Australia) with Indonesia engaging in several conflicts with the Dutch to get West New Guinea back and also went to war with Malaysia. Indonesia is supplied with weapons by the Russians and eventually, Indonesia takes over West New Guinea and renames it Irian Jaya and starts making moves towards Malaysia as well. Australia is worried about the moves that Indonesia are taking. Australia then helps America with the Vietnam War without being asked and this makes America think that they owe Australia a favour. This is in case Indonesia attacks Australia, America may help them. America tells Australia to get South Vietnam to request for their help to prevent public backlash (so America doesn't look like a war bringer).

Other Reasons Australia Went to Vietnam

 * Look at the official reason given to the public by Menzies (because South Vietnam requested help)
 * The REAL reason (fear of Indonesia)
 * Alliances and treaty obligations
 * National self interest
 * International morality
 * The nature of the war (invasion or civil war)
 * Regional responsibilities
 * Cold war ideology (communism/democracy)