All wars boil down into it's basic components. Fighting over limited resources.

The Japanese needed oil and iron, and the Germans needed lebensraum (living space). It was a popular concept in 19th and 20th century Germany, getting more land for expansion. If fact Hitler compared the "lebensraum" invasion of Russia to the USA's "manifest destiny" western expansion.

The details and characters might change throughout history, but humans are always fighting over the same things.