The Armada of the Strait under Don Diego Flores de Valdes in 1581-84 came at a crucial juncture in global politics. Philip II of Spain had assumed the crown of Portugal and its overseas empire, and Francis Drake's daring peacetime raids had challenged the dominance of Spain and Portugal in the Americas. The armada was intended to ensure the loyalty of Portuguese Brazil; bolster its defences against hostile native peoples, and English and French pirates and interlopers; and fortify and settle the Strait of Magellan to prevent further incursions into the Pacific.

Pedro de Rada, the...