The Philadelphia region was a major contributor to the war effort. The Frankford Arsenal was a vital source of small-arms, ammunition, artillery shells, and time fuses to the Federal army and state militia. The Philadelphia Navy Yard provided an important source of ships, sailors, and supplies for the United States Navy during the war. The vast majority of the coal used by the Navy for its warships and blockaders came from underground mines in several counties in northern Pennsylvania. The Satterlee Hospital and the Mower Hospital (both near Philadelphia) were significant military hospitals and rehabilitation centers, as was the York U.S. Army General Hospital.