the Nicaeans went on the offensive, and advanced quickly westwards along the Via Egnatia. Michael II of Epirus, who was encamped at Kastoria, was caught off guard by the rapidity of their advance, and when the Nicaeans crossed the pass of Vodena to face him, he was forced to hastily retreat with his troops across the Pindus mountains to the vicinity of Avlona, held by his ally Manfred. There the final negotiations for the marriage between Manfred and Helena were concluded: the wedding took place at Trani on 2 June 1259. In their retreat, which continued even during night, the Epirotes reportedly lost many men in the dangerous mountain passes, while the Nicaean generals captured Ohrid and Deavolis and other cities. Opposing forces The Epirote ruler had lost much of his territory, but soon his Latin allies came to his aid. Manfred, preoccupied with his conflicts against the Guelphs in central Italy, did not come in person–although his presence is erroneously reported by near-contemporary sources like Nikephoros Gregoras and Matteo Spinelli—but sent 400 superbly outfitted German knights, who probably landed at Avlona to join Michael II's forces. William of Villehardouin on the other hand campaigned at the head his forces. The Greek and French versions of the Chronicle of the Morea mention troops from Achaea, the Duchy of Athens, the Triarchy of Negroponte, and the Duchy of the Archipelago under William's command, implying a general feudal levy from the Frankish states of Greece, which were vassals of the Prince of Achaea. Many of the most distinguished nobles of Frankish Greece also took part in the expedition. The Achaean host crossed the Gulf of Corinth at Naupaktos and marched to the Epirote capital of Arta, before crossing the Pindus at joining the forces of the other Frankish states at Thalassionon (possibly Elassona in northern Thessaly). Michael of Epirus in turn was accompanied by his elder son Nikephoros and further aided by his bastard son John Doukas, who brought with him many Vlachs from the Great Vlachia region of Thessaly. The Aragonese Chronicle of the Morea gives the totals of 8,000 heavily-armed and 12,000 lightly-armed troops for William's army, including twenty dukes, counts, and barons; and 8,000 heavily-armed and 18,000 lightly-armed troops for the Epirote army. These numbers are universally considered as much exaggerated by modern historians. On the Nicaean side, the army comprised not only native Greek contingents from Asia, Macedonia