According to Official Guinness Records,
Lothar von Arnaud de la Perière (the captain of the German submarine U-35) fought in the German Imperial Navy in World War I, during which he sank an astounding 194 ships with a total tonnage of 454,000 Gross Registered Ton (GRT). In many cases the vessels were unescorted merchant ships, meaning that the submarine's crew would board the vessel, inspect its cargo, and allow the crew to board lifeboats. It would then be sunk using the sub's 88 mm (3.5 in) deck gun to conserve torpedos. Even though he was operating in the very early days of practical submarine warfare, de la Perière's achievement remains unmatched to this day. A third tank commander, Walter Schroif, is credited, by some, with 161 kills, but there are currently no records to substantiate this claim.
For a complete list of Unknown date records, please visit Unknown date Guinness Records in Germany.