The Type X (XB) U-boat was a class of large minelaying U-boats built for Nazi Germany's Kriegsmarine from 1939 to 1945. Eight were built during World War II. Although intended as long-range mine-layers, they were mainly used as supply submarines, a task they shared with the Type XIV. By 1944, six were lost and the two remaining Type XB boats were converted to transport submarines to bring valuable cargo to Japan. At the end of the war, one surrendered at sea to the United States Navy and the last one was captured by the Imperial Japanese Navy at the German base of Jakarta.