Hildebrand's election as Pope Gregory VII marked the beginning of one of the most consequential papacies of the Middle Ages. His insistence on papal supremacy over secular rulers in matters of clerical appointment ignited the Investiture Controversy, a struggle that would humble Emperor Henry IV at Canossa and reshape the balance of power between church and empire for centuries.
Hildebrand, a Tuscan-born monk who had served as an advisor to several popes, was acclaimed pope by the Roman clergy and populace with unusual speed and enthusiasm on May 22, 1073, even before the formal conclave process was fully observed. He took the name Gregory VII in honor of his mentor Gregory VI.
Gregory's papacy became synonymous with reform: he battled simony, clerical marriage, and above all, the practice of lay investiture, in which kings and nobles appointed bishops and abbots. His 1075 decree banning lay investiture set him on a collision course with Henry IV, the Holy Roman Emperor, culminating in Henry's famous barefoot penance in the snow at Canossa in 1077.
The conflict didn't end there—Gregory was later driven from Rome and died in exile in Salerno in 1085—but his papacy permanently altered the relationship between spiritual and temporal authority in Europe, establishing precedents for papal power that would echo for centuries.
Key people: Pope Gregory VII, Henry IV