When John III ascended the throne in 1521, Portugal’s political structure was much the same as that of any other important European power. Portugal’s first king, Alfonso Henriques, won a decisive victory against the Moors and independence from Spain in the twelfth century. By the turn of the 16th century, the nation was unified and power was firmly vested in the king; the sovereign assembled the ... [Show full abstract] estates at will, and only at long intervals. This system was like those of Spain and France; but as to her foreign policy, Portugal moved in a direction dictated by her own national purposes. A comparison of Portuguese with Spanish history during the period of John III shows this clearly. John’s reign covered approximately the same years as that of Charles V in Spain; the Spanish king began his rule two years before John’s succession and abdicated two years before John died. Both rulers had acquired colonial empires, but while Charles V combined his overseas responsibilities with European power politics, Portugal’s king concentrated his efforts on guarding and strengthening his colonial possessions.