Gregor X

Gregor X was a pope who served from 1271 to 1276 and is known for presiding over one of the longest papal conclaves in history, which lasted nearly three years before his election. His papacy was marked by efforts to reform the church and improve relations with the Eastern Orthodox Church. His election followed a tumultuous period of sedisvakanz, reflecting the complexities and challenges of papal succession during the medieval era.