During the Second World War, both the American and the Japanese Navies built a number of seaplane tenders to supplement their aircraft carrier fleets. However, these ships often had their catapults removed, and were used as support vessels that operated seaplanes from harbours rather than in a seaway. These aircraft were generally for long range reconnaissance patrols. The tenders allowed the aircraft to be rapidly deployed to new bases because their runways did not have to be constructed, and support facilities were mobile much like supply ships for submarines or destroyers.