Complex sentence: The representatives of the counties and the Székely and Saxon seats assembled at Bábolna (now Bobâlna in Romania) and signed a "brotherly union" on 16 September, pledging that they would to assist each other against all but the monarch.
Split into simpler sentences: The representatives of the counties and the Székely and Saxon seats assembled at Bábolna (now Bobâlna in Romania). They signed a "brotherly union" on 16 September, pledging that they would to assist each other against all but the monarch.