Whaht cause the WW1?

WWI is history, it has ended, so you should use the past tense. *Special note, world war 1 and 2 are famous historical events, the 'the' before it can be omitted if you mention the full name world war 1.

1. What cause the war?

What caused the war? or What were the causations of the war?

2. What are the factors causing the war?

What were the factors that caused the war?

Good Luck!!!

You should use past tense (WWI is a past event).

1. What caused the war?
2. What were the factors causing the war?