How did Henry IV gain control of Rome in 1084?

After failing to capture Rome in 1081 and 1082, Henry IV successfully gained control of the city in March 1084. His victory was facilitated when the Romans, including many cardinals and other clergy, deserted the cause of Pope Gregory VII due to his perceived inflexibility and opened the city gates to Henry and his army.12

Following the capture of the city, Henry IV enthroned Guibert, the archbishop of Ravenna, as the antipope Clement III. On March 31, 1084, Clement III crowned Henry as emperor. Gregory VII initially sought refuge in the Castel Sant’Angelo before fleeing to Salerno, where he eventually died in exile.12