During the civil war, the union navy

The Union Navy was the United States Navy (USN) during the American Civil War, when it fought the Confederate States Navy (CSN). The term is sometimes used carelessly to include vessels of war used on the rivers of the interior while they were under the control of the United States Army, also called the Union Army.

Hope this helps

protectionism fosters competition and keeps price regulated is not an argument in favor of protectionism.