Benevento was forced to make submission to the Byzantine Empire, whose Italian catepan Boioannes had built the fortified city of Troia nearby.
After making submission to the Western Emperor, Landulf is not heard of again in the pages of history until his death and his son takes his place.
Henry III, angry at being denied, immediately laid siege to the city and Pope Clement II excommunicated Landulf and Pandulf and the citizenry.
The siege was eventually lifted, however, the disrespect shown the imperial family and the church coupled with the principality's decline caused Pandulf's brother, Daufer (later Pope Victor III), to flee the city and take refuge with Guaimar IV of Salerno.
In the aftermath of the Battle of Civitate in 1053, in which the pope was imprisoned in Benevento, the city invited Pandulf and Landulf back (sometime between June 1053 and March 1054).