Germany.
australians involvment in ww1
Japan
Germany was Britain's main enemy.
They were not placed anywhere. Japan was not an enemy in World War I.
The question is unanswerable as asked since it does not define who the "enemy" is.
Australias' northern cities, Darwin and Broome, were repeatedly bombed by Japanese aircraft during World War 2.
Germany and Japan
I would say Germany. Although Japan was a big enemy.
Japan
Russia.
ASDIC