LXXX '80 Reais' - Filipe I

Philip II of Spain became Philip I of Portugal in 1581 following the dynastic crisis triggered by King Sebastião's death at the Battle of Alcácer Quibir in 1578, which left the Portuguese throne vacant and ultimately enabled the Iberian Union. The 80 Reais denomination was struck to satisfy Portuguese commercial demand during this uneasy annexation, using a fineness standard inherited from earlier Manueline-era silver coinage rather than conforming to Castilian monetary practice — a deliberate concession to keep Portuguese trade networks functioning without disruption.