Help if u know please

Which of the following is one example of an ideological conflict that became one of the causes of world war ii?

1. the fifteenth amendment guaranteed for all us citizens, regardless of "previous condition of servitude." freedom citizenship voting rights religious tolerance 2. which group was still not allowed to vote following passage of this amendment? women poor men rich men former slaves 3. the fifteenth amendment was the last of the amendments. carpetbagger lincoln reconstruction scalawag

Why did the free african americans fight for the patriot cause and explain why enslaved africans volunteered to fight for both sides