The chrysobull that Theodore Laskaris granted to Venice in 1∧19 was evidently no more than a gesture. It was never revoked, but it was never renewed. The greatest of the emperors at Nicaea, John III Vatatzes, who succeeded Laskaris in 1222, aimed to make his empire self-sufficient, not dependent for its economic survival on trade with the Italians. Nor was he keen to do business with them in Constantinople. If and when his ships sailed into the Golden Horn it would be to take the city from them, to overthrow the Latin regime and restore the Byzantine Empire. The regime was already tottering. Its new emperor, Robert of Courtenay (1221–8), was a self-indulgent youth with none of the adventurous spirit which had fired the leaders of the Fourth Crusade. The French principality in the Morea and the French Duchy of Athens and Thebes which they had founded seemed to have a future. But the Latin Empire of Constantinople, of which they were fiefs, could not survive without a new influx of manpower and resources. The first of its outposts to fall was the so-called Kingdom of Thessalonica. Theodore of Epiros had dealt a memorable blow to the Latin regime by capturing its emperor in 1217. In the next few years he capitalised on his success by expanding his dominions at the expense not only of the Latins in Thessaly but also of the Bulgarians in Macedonia. His supporters confidently predicted that Thessalonica would soon fall to him and that, once master of the second city of Byzantium, he would have a better claim to the imperial title than any emperor in Nicaea.