Pope Urban III
On 23 December 1189, an agreement was reached between the Chapter of S. Vincenzo and the Chapter of S. Alessandro to unite as a single body of Canons. The arrangement was approved by Pope Clement III on 21 June 1190. The two Chapters had been quarrelling for more than a half century, despite the examination of their case by three cardinals, and demands from Pope Lucius III, Pope Urban III, and Pope Gregory VIII that they settle their differences.