On 2 July 911, Landulf signed a treaty with Duke Gregory IV of Naples, part of a policy of alliance and friendship with his fellow Christian rulers of the Mezzogiorno.
Together the Greco-Lombard army joined the northern forces of Pope John X and Alberic I of Spoleto and vanquished the Saracens at the Battle of Garigliano.
According to Liudprand of Cremona, Landulf, a "potent prince", in answering a request for advice from the pope, initiated the alliance that brought an end to the Saracens on the Garigliano.
Within a few years, Landulf's successful anti-Byzantine policy had been reversed and he was forced to make peace, but clashes continued: at Siponto in 936 and at Matera in 940.
In 937, a band of Hungarians marched from Burgundy to Italy via the Rhone valley in the service of King Hugh, who sent them against Monte Cassino, Naples and Capua,[2] plundering and destroying all before them.