 Complete the following phrase:  A royal charter issued on 26 July 1324 is the first document to reference Basarab. According to the charter, he was subject to Charles I of Hungary as the voivode of Wallachia. Basarab became disloyal to the Holy Crown of Hungary in 1325. He seized the Banate of Severin and raided the southern regions of the Kingdom of Hungary. Basarab supported Michael Shishman of Bulgarias attack against the Kingdom of Serbia, but their united armies were defeated in the 