Context: The American Civil War was the costliest war for the U.S. in terms of casualties. After most slave states, located in the southern U.S., formed the Confederate States, C.S. troops led by former U.S. Army officers, mobilized a very large fraction of Southern white manpower. Forces of the United States (the "Union" or "the North") formed the Union Army consisting of a small body of regular army units and a large body of volunteer units raised from every state, north and south, except South Carolina.[citation needed]

Question: Which war had the most U.S. casualties associated with it?
Answer: The American Civil War

Question: What were the U.S. forces referred to as?
Answer: the "Union" or "the North"

Question: What state did not contribute any troops to the Union Army?
Answer: South Carolina

Question: Which war had the least U.S. casualties with it?
Answer: Unanswerable

Question: What were the Southern forces referred to as?
Answer: Unanswerable

Question: What state contributed the most troops to the Union Army?
Answer: Unanswerable

Question: What was the least expensive war for the U.S.?
Answer: Unanswerable