Many Australians became such after migrating from war-torn countries or - like myself - are children of such immigrants (my mother and her grandparents are Estonian, and left Estonia during the Russian invasion of Estonia during WWII). You are correct that Australia hasn't suffered an 'invasion' (putting aside, yes, the invasion of Aboriginal Australia), but I do believe there are many current-day Australians who have a very good idea what a 'real war' can do to you, your loved ones and society in general.