Many British naval vessels carried float planes, seaplanes or amphibians for reconnaissance and spotting: two to four on battleships or battlecruisers and one on cruisers. The aircraft, a Fairey Seafox or later a Supermarine Walrus, were catapult-launched, and landed on the sea alongside for recovery by crane. Several submarine aircraft carriers were built by Japan, each carrying one floatplane, which did not prove effective in war. The French Navy built one large submarine, which also carried one floatplane, and was also not effective in war.