Groat - Martin I Barcelona

Martin I, who inherited the Crown of Aragon in 1396 following the childless death of his brother John I, ruled Catalonia during a period of acute dynastic anxiety. He died in 1410 without a legitimate heir, triggering the Compromise of Caspe in 1412 — one of the earliest recorded exercises in quasi-constitutional succession arbitration in medieval Europe — which handed the Crown to the Castilian Trastámara line and permanently altered the political trajectory of the Iberian peninsula.

The Cru#511 attribution places this squarely within the Barcelona mint's output for his reign, a relatively short fourteen-year window.