Why was so much of the death and destruction in World War 2 targeted at civilians?
This is an interesting question and difficult to answer. I'm
adding a link to the Wikipedia article on total war, though there's
much in the article that I don't agree with. Obviously, part of the
reason was the concept of 'total' war, which really goes back to
WW1. It was no longer simply a matter of armies and navies fighting
one another, but the entire industrial capacities of nations were
pitted against one another. Workers in the armaments industries,
transport industries and so on were also in the front line.
Clearly, the devlopment of bomber aircraft was highly significant.
However, the very highest casualties were on the Eastern Front in
Europe, in the death camps and in the Far East and weren't directly
related to the war of industrial capacities. So the issue isn't at
all simple. Total War is a concept that the best way to defeat the
enemy is to destroy his capacity and will to fight. Therefore, his
factories, supplies and resources have to be destroyed and these
were usually located near cities or were operated by civilian
labors. General Tecumseh Sherman realized this when he began his
"march to the sea" in the Civil War in 1864. General Sherman's army
cut a path of destruction from Atlanta(the main manufacturing
center of the Confederacy) thru Georgia to Savannah. This had the
effect of discouraging the Confederate soldiers and made they fear
for their families.