Because they were thought to relieve sins if you had been sinful in your life. You see, it's all to do with religion and faith The pilgrims would go to a shrine, and pray to God for the dead person. The reason for this is because during that time people could not find any other explanation for things, so they would relate it to magic and God and religion etc.But it would make a lot of sense to a religious person.
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.