The Butterworth Squadron was a British commercial group of three vessels, Butterworth, Jackal, and Prince Lee Boo, that sailed for the Pacific Ocean from London via Cape Horn in late 1791. The principals financing the expedition were Alderman William Curtis, London ship-owner Theophilus Pritzler, and probably John Perry, a Blackwall shipbuilder. The leader of the expedition was Captain William Brown, an established whaling captain from the Greenland whale fishery. Sigismund Bacstrom, a naturalist who had previously sailed as a secretary to Sir Joseph Banks, was the surgeon for the expedition. Bacstrom produced a number of drawings during the first part of the voyage, some of which are still in existence.