"The only good (and moral) reason there ever has been to fight a war was the legitimate defence of one's own homeland against a direct attack by a foreign entity... and the legitimate resistance against invasion of one's homeland and the occupation of it by foreign armies."

I will still state that, by your criteria, the present conflict (Palestinians/Israel) in the middle east is moral on BOTH sides, and the entire actions of boths sides in WW II was immoral. Please let me know how you can consider otherwise, by your statement.

So, at what time did Germany ever invade Canada?

Or Australia?