BISMARCK ARCHIPELAGO, the collective name of a large number of islands lying north and north-east of New Guinea, between I° and 7° S., and 146° and 153° E., which were a German protectorate from 1885, but under the Treaty of Ver sailles (1919) were made part of the mandated territory of New Guinea and mandated to Australia. The largest island is New Britain (formerly New Pomerania), and the archipelago also includes New Ireland (formerly New Mecklenburg), Lavongai (formerly New Hanover), with small attendant islands, the Admiralty islands and a chain of islands off the coast of New Guinea, the whole system lying in the form of a great amphi theatre of oval shape. (See ADMIRALTY ISLANDS ; NEW IRELAND ; NEW BRITAIN ; NEW GUINEA.)