In the following year the headquarters of the African Company was removed from Pillau to Emden. This latter town was not situated on Brandenburg soil, and the manner in which the Elector secured a footing in it is both instructive and characteristic of his easy methods of intervening and making a good bargain wherever an opportunity presented itself. It chanced that at that time the Estates of East Frisia were at loggerheads with their ruler, and they appealed to Frederick William for assistance. Nothing loth, he landed a force by night, and by a surprise attack seized the castle of Greetsiel, which thus became his naval base. By an agreement with the town of Emden he subsequently acquired the right to station within its walls a "compagnie de marine" for the service of the African Corporation. This force, which was gradually increased to three, and temporarily to four, companies, and ultimately received the name of the "Marine Battalion," was drawn upon to man both the ships and the forts in Africa. The transfer to Emden brought other advantages besides an ice-free port, a base on the North Sea, and an abbreviation of the route to Gross-Friedrichsburg, for the East Frisian Estates and the Elector of Cologne were both persuaded to invest largely in the African Company in consequence of the change. In the year of the Emden agreement, the Brandenburg Navy was formally founded by the establishment of an "Admiralty" at Berlin. The Cabinet order by which this institution was created shows that the fleet then in full possession of the State comprised 10 ships, with 240 guns, while Raule was still under contract to provide 17 further vessels. The permanent personnel consisted of 1 vice-commodore, 5 naval captains, 3 officers of Marines, 12 mates, and 120 seamen. In 1686, the Elector took the Company entirely into his own hands, and simultaneously acquired a station on the island of St. Thomas, in the West Indies, as a place of call for the ships engaged in the slave traffic. He had also at that time made preparations for forming an East Indian trading company (at a much earlier date he had unsuccessfully attempted to acquire Tranquebar, on the Coromandel Coast, from the Danes) and for fitting out an expedition to China and Japan. These schemes, however, came to nothing.