This threat became especially acute after Roger II of Sicily made himself supreme in southern Italy and assumed the title of king. Emperor Lothair III had Byzantine backing, including a large financial subsidy, for his invasion of Norman territory in 1136, which reached as far south as Bari. Pope Innocent II, with the Church's possessions in Italy under threat by Roger II, who supported Antipope Anacletus II, was also party to the alliance of Lothair and John II. However, this alliance proved unable to resist Roger, who extracted by force a recognition of his royal title from the Pope in 1139 (Treaty of Mignano). Lothair's successor Conrad III was approached in 1140 for a royal German bride for John's youngest son Manuel. Bertha of Sulzbach, Conrad's sister-in-law, was chosen and despatched to Byzantium. At much the same time Roger II applied to John II for an imperial bride for his son, but was unsuccessful. John's penchant for interfering with his wife's family, the rulers of Hungary, was problematic. The welcome accorded to ousted claimants of the Hungarian throne in Constantinople was seen by the Byzantines as a useful insurance policy and source of political leverage. However, the Hungarians treated this interference as a fighting matter. A Hungarian alliance with the Serbs produced serious consequences for continued Byzantine dominance in the western Balkans. In the East John attempted, like his father, to exploit the differences between the Seljuq Sultan of Iconium and the Danishmendid dynasty controlling the northeastern, inland, parts of Anatolia. In 1134 the Seljuq sultan Mas'ud provided troops for John's attack on the Danishmend-held city of Kastamuni, however, the alliance proved unreliable as the Seljuq troops abandoned the expedition, decamping during the night. In the Crusader states of the Levant it was generally admitted that the Byzantine claims over Antioch were legally valid, though it was pragmatically viewed that only when the Byzantine emperor was in a position to enforce them militarily were they likely to be recognised in practice. The high point of John's diplomacy in the Levant was in 1137 when he extracted formal homage from the rulers of the Principality of Antioch, County of Edessa and the County of Tripoli. The Byzantine desire to be seen as holding a level of suzerainty over all of the Crusader states was taken seriously, as evidenced by the alarm shown in the Kingdom of Jerusalem when John informed King Fulk of his plan for an armed pilgrimage to the Holy City (1142).