They were under what is referred to as the first covenant. Jesus is the intercessor for sins and essentially takes away the sins of the world. People who lived before Jesus had their sins forgiven by making animal sacrifices.
You can read about this in the book of Leviticus.
When Jesus Christ died on the cross for our sins, s blood sacrifice also covered the sins of Old Testament saints. Thus, the forgiveness received in the Old Testament was based on Christ's atonement.
2 Kings 2:11 gives one example (there are many more) of an Old Testament saint who went to heaven. "As they were walking along and talking together, suddenly a chariot of fire and horses of fire appeared and separated the two of them, and Elijah went up to heaven in a whirlwind.
Thus, all saints who died before Christ died knowing the hour would come when Christ would actually die as that spotless Lamb of God in place the animal sacrifices of their day (i.e. - Isaiah 53:5, Job 19:25-26, Zechariah 9:9, Genesis 3:15, 22:8) .
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.