Pope Stephen III
The brothers maintained lukewarm relations with the assistance of their mother Bertrada, but in 770 Charles signed a treaty with Duke Tassilo III of Bavaria and married a Lombard Princess (commonly known today as Desiderata), the daughter of King Desiderius, to surround Carloman with his own allies. Though Pope Stephen III first opposed the marriage with the Lombard princess, he found little to fear from a Frankish-Lombard alliance.