WW2 Australian involvement By neonleon Sep 1, 1939 Germany Invades Poland Period: Sep 1, 1939 to Dec 12, 1945 WW2 History for australia Sep 3, 1939 Britain declares war on Germany Sep 3, 1939 Australia alongside New Zealand also declares war on Germany Under Prime Minister Robert Menzies Mar 1, 1940 7th Division is formed day unknown