not a diplomatic mission, but a military one. The armada was to avenge the Zamorin's mistreatment of Cabral and the massacre of the Portuguese in the Calicut factory (see 2nd India Armada for details). The 4th Armada did not set out with enough manpower to conquer Calicut outright. Rather, they expected a strong show of force was enough to intimidate the Zamorin into compliance. They would do this by cutting off Calicut's lifeline - its trade. In the pre-launch plans, the first squadron under Vasco da Gama was supposed to set up a naval blockade of Calicut harbor and prevent the entry of any ships, while the second squadron of Vicente Sodré was to patrol the Gulf of Aden and bottle up Arab shipping in the Red Sea. This, it was thought, would be enough to bring the Zamorin to his knees and sue for terms. The terms envisaged was for the Zamorin to make amends for the factory and restore the Portuguese trade on the Malabar coast (Gama was under instructions to accept nothing less than a fixed price guarantee this time). The Zamorin would also be obliged to prosecute those they identified as the intriguers behind the massacre and expel all Arab merchants from any and all ports under Calicut's sway. The armada is said by the chroniclers to have been given explicit instructions to establish factories (feitorias) in Cochin and Cannanore, Calicut's rival cities on the Malabar coast of India, which had opened good relations with Cabral. However, we know of only one designated crown factor carried by the 4th Armada - Diogo Fernandes Correia. This has led some historians to suspect that maybe this was only a back-up plan at best. In other words, that it was envisaged that once the quarrel with the Zamorin was resolved, Portuguese operations would be centered on Calicut again, with Diogo Fernandes Correia as factor there, and that the other smaller cities, with their smaller markets, would just fade again into the background. Finally, the 4th Armada was instructed to open trade with the East African city-state of Sofala. Sofala had been secretly visited by the explorer Pêro da Covilhã during his overland expedition back in 1487, and he identified it as the end-point of the Monomatapa gold trade. The Portuguese crown had been eager to tap that gold source, but all prior armadas had failed to find it until