Vlad left Buda for Poland without Sigismund's authorization in early 1423, but was captured before reaching the border. Before long, Sigismund acknowledged Dan II as the lawful ruler of Wallachia. The Byzantine historian, Doukas, recorded that Vlad was "an officer in the army" of the Byzantine Emperor, John VIII Palaiologos, and he "had access" to the imperial palace in Constantinople. Historian Radu Florescu says that Sigismund had appointed Vlad to receive John VIII (who had come to Italy to seek assistance against the Ottomans) in Venice in 1423, and Vlad accompanied the emperor back to Constantinople. After realizing that John VIII could not help him to seize Wallachia, Vlad returned to Hungary in 1429.