An opportunity was afforded him in 1534, when the Muhammadan King of Bengal asked for the help of a Portuguese force against the Afghán invader, Sher Sháh. Nuno da Cunha promised his assistance, and at once sent a fleet of nine ships, carrying 400 Portuguese soldiers under the command of Martim Affonso de Mello Jusarte. The Portuguese contingent behaved gallantly, and its deeds are described in the first twelve chapters of the ninth Book of the fourth Decade of João de Barros, the contemporary Portuguese historian. Nuno da Cunha intended to follow in person, but he was prevented by the condition of affairs in Gujarát. It happened therefore that Portuguese authority was never directly established in Bengal. No royal factory or fortress was erected, and the Portuguese settlement at Húglí, where goods were collected for shipment to Portugal, was loosely considered to be subject to the Captain of Ceylon. The Portuguese in North-Eastern India remained to the end adventurers and merchants, and were never a ruling power. The important events which prevented Nuno da Cunha from visiting Bengal were closely connected with the threatened approach of Suláimán the {180} Magnificent's fleet from the Red Sea. It was well understood that that fleet would sail direct to the coast of Gujarát as the fleet of Emir Husain had done thirty years before. This knowledge made Nuno da Cunha very anxious to establish the Portuguese in a strong position on the coasts of North-Western India. Their main station in this neighbourhood had hitherto been the port of Chaul, where they had a factory and a small fortress. Portuguese agents were likewise established in the ports of Gujarát, but they were in no place masters of a strong defensive position. To obtain a fitting site for a fortress in Gujarát was a principal aim of Nuno da Cunha's policy; not only for defence against the Muhammadans in India, but also as a bulwark against the expected Turkish fleet. Circumstances favoured him. The Mughal Emperor Humáyún was engaged in war with Bahádur Sháh, the King of Ahmadábád or Gujarát. In his extremity Bahádur Sháh sought to make an alliance with the Portuguese, and for this purpose he granted them the island of Bassein, which was then separated from the mainland by a narrow creek. Bassein lies about twenty-eight miles north of Bombay, and afterwards became the northern capital of Portuguese India, almost rivalling Goa in splendour and prosperity. At Bassein the Portuguese built a fort, but the place was not naturally defensible, and Nuno da Cunha set his heart on the possession of the rocky island of Diu, which had been one of the spots designed by Albuquerque for a Portuguese stronghold.