How does the Constitution distribute war powers between the President and Congress, and why did the Founders decide on this arrangement?

The Constitution of the United States divides the war powers of the federal government between the Executive and Legislative branches: the President is the Commander in Chief of the armed forces (Article II, section 2), while Congress has the power to make declarations of war, and to raise and support the armed forces. The founding father did this to prevent the majority from ruling with an iron fist.