What role did imperialism play in ww2?
Both Nazi Germany and Imperial Japan wanted world empires, they both started WWII in large part to get, to keep, to expand, restore empires.
Depends on your definition of "imperialism." Technically, European imperialism died in WW1. That said, Germany was trying to take over Europe, possibly the world, saying they needed the "living room" (i.e., liebensraum). Japanese imperialism, though, was alive and well and was the motive for attacking Pearl Harbor. The US had cut off Japan's oil supply with such effect that Japan could not continue its imperialistic march through East Asia and the Pacific, invading country after country. Germany, having just invaded the Netherlands, gave Japan the Dutch West Indies, an oil producer that could meat its fuel demands, in exchange for Japan attacking the US, which Hitler thought would embroil the US in a war in the Pacific and FDR wouldn't be so reckless as to open a two-front war by entering the European theater. Hitler was wrong, and it cost him the war because he went and attacked the USSR thinking the fall of the UK was imminent and that the US would not come to the UK's aid.
It was all about expanding their territory and domination with the axis powers. Japan and Germany invaded and conquered many nations before their ultimate defeat. Italy did too, but to a far lesser degree than Germany and Japan.
Germany wanted to expand and reclaim their former glory, uniting German-speaking people and gaining back all their territory. Italy wanted to imperialism and create a “new Rome”, starting with Ethiopia and going from there. Japan wanted to expand as much as possible, conquering the whole East (Korea, Manchuria, China, Indochina and all the islands in the Pacific), and countries like England, America, France and all wanted to keep their territories from the age of imperialism (America with Hawaii, Guam and the Philippines, England with Australia and several other regions (at least I think Australia was still controlled by them) and things like that.