Another of the results of the cessation of Portuguese hostilities was that Nassau now sent Admiral Jol, with two thousand troops, against _St. Paul de Loanda_, the most important Portuguese possession in Africa. It fell into the hands of the Dutch without much opposition, thus causing a grievous loss to the Brazilians, whose entire supply of negro slaves came from this source. It was not solely a loss to them as slave-traders; but without a supply of slaves their Brazilian possessions were almost worthless. The Dutch Company established a government in _Angola_ independent of that of _Recife_. From _Loanda_ Admiral Jol proceeded against the island of _St. Thomas_, which place, after a siege of fourteen days, surrendered. The climate, however, made the Dutch pay a severe penalty. It is said that but a tenth of the invading force escaped death or disease, Admiral Jol himself being one of the victims. [Sidenote: 1637, 1648.] It is now necessary to revert to the northern portion of Brazil, which, being separated by the scene of the Dutch conquests from the seat of government at _San Salvador_, had hitherto remained unaffected by the war. In this part of the world some English adventurers endeavoured unsuccessfully to obtain a footing; but the chief incidents to be related are an endeavour to discover the sources of the _Amazons_, and a slave-hunting expedition of the younger Maciel, as great a villain as his father, and who was now governor of _Pará_. The origin of the former expedition was a voyage of some missionaries who had been sent to the natives from _Quito_, and who had been taken to the river _Napo_. Down this stream they were, like Orellana, carried to the _Amazons_, and like him they were borne on that river to the ocean. Soon after their arrival at _Belem_, an expedition was concerted to explore the river upwards, taking the missionaries as guides. Of this exploring party Teixeira took the command, with seventy soldiers and twelve hundred natives, and in due time he arrived at _Quito_, where he was received with great rejoicings.