As mentioned earlier, Friedrich Christiansen
achieved a number of his victories (if not all) while flying seaplanes. He was flying one when he attacked a British submarine in the Thames estuary. It is often reported that he sunk it, which is not true, but he came close. The Captain and a number of crewmen were killed on the bridge, but the stricken sub managed to return to base before it foundered. In all, quite a feat in those days.