His uncle Pope Innocent IV appointed him cardinal. He was legate to England (1265–68), charged with establishing peace between the English king Henry III and the rebellious barons in 1265. Elected as successor to Innocent V on July 11, he died a little more than a month later, having, however, revoked the stern conclave regulations of Pope Gregory X. Adrian died before he was ordained a priest or consecrated. Dante in his Purgatory (XIX, 97–126) portrays him as lamenting his avarice and acknowledging “how the great mantle weighs” and “so justice here holds us close.”