Calicut's spice-trade defenses were built for rival traders, not Portuguese guns

For centuries the Zamorin of Calicut had held Malabar's pepper trade with a cheap, proven toolkit: fast oar-and-sail paraos to patrol the coast, tariff and tribute deals with the Arab and Mappila merchant guilds who financed and carried the cargo, and alliances with neighbouring Indian Ocean powers. It worked because the rivals it was built against were other traders sailing the same kind of ships.

In 1500 a riot destroyed Pedro Álvares Cabral's Calicut trading post after a dispute over the Arab merchants' hold on the pepper trade; Cabral answered by bombarding the port. Vasco da Gama returned in 1502 with a new instrument, not just more force: the cartaz, a Portuguese-issued sailing pass. A ship without one was fair game, and da Gama burned the pilgrim ship Miri and bombarded Calicut again to make the point stick.

In 1503 the Zamorin sent his fastest ships — light, fast, manned by Arab captains — against a Portuguese fleet sailing in line and firing broadside after broadside. The light ships that had always been enough against rival Malabar and Arab fleets could not out-gun carracks built for ocean crossings, and they were shredded before they could close to grapple.

The Zamorin's answer was to widen the coalition, not change the ships. In 1509 his vessels joined a Mamluk-Egyptian and Gujarati fleet of roughly a hundred boarding-oriented ships at Diu. A Portuguese force of about eighteen heavily gunned ships broke it in a single day, and Portuguese command of the Malabar sea lanes — and the cartaz — went unchallenged from Calicut for the rest of the century.