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OK I think most of us know about the 1580 succession crisis in Portugal, but for those who don't know here's some background info. In 1578 King Sebastian of Portugal invaded Morocco, officially to restore the deposed Sultan Abu Abdallah Mohammed II, but in reality a misguided goal of relaunching the Crusades and, along with much of his army, was killed at the Battle of Alcácer Quibir. As Sebastian was unmarried and childless, the throne passed to his great-uncle Cardinal-Infante Henry, who in turn also died unmarried and childless in 1580, triggering the crisis over who would inherit the throne.

The candidates, all descendants of King Manuel I, were António, Prior of Crato, the illegitimate (though he claimed otherwise) son of Manuel I's second son the Duke of Beja, Catherine, Duchess of Braganza, daughter of Manuel's sixth son (but the only other male issue of Manuel to marry and have heirs ) the Duke of Guimarães and finally King Felipe II of Spain, son of Manuel's eldest daughter Empress Isabel. The throne eventually when to the weakest claim, Felipe of Spain, after he invaded Portugal and took the throne by force.

However, a few years earlier there had been another Infante with a better claim then all three of the contenders, Infante Duarte, 5th Duke of Guimarães, brother to the Duchess of Braganza and the only legitimate male-line heir of Manuel I besides Sebastian and the Cardinal-Infante. Unfortunately, the Duke died (some say by his own hand) in 1576, after a row with King Sebastian.

If Infante Duarte hadn't died/committed suicide and Sebastian still died in battle (which was fairly likely considering the King's obsession with Crusading and conquering Morocco) then the Duke would have became Duarte II in 1580 when the Cardinal-King died. So what if he lived? Obviously Portugal would remain independent, but what else changes? How does the Portuguese Empire develop if its not bound to Spain and threatened by the Dutch? Who does Duarte II marry? Would Portugal, which under the last Avizs had kept out of most European affairs, have a more active foreign policy? Does this help or hinder Spain's wars with the Dutch and England? Please discuss:D!
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