Complex sentence: After that, he moved to the court of his first cousin Vlad III Dracula and, in 1457, managed to receive 6,000 horsemen as military assistance, putting them to use in a victorious battle against Petru Aron at Doljești, near Roman.
Split into simpler sentences: After that, he moved to the court of his first cousin Vlad III Dracula. In 1457, with Vlad's help, he managed to receive 6,000 horsemen as military assistance, putting them to use in a victorious battle against Petru Aron at Doljești, near Roman.