Battle of Plassey
The British took gradual control of Bihar after the Battle of Plassey (1757). Mir Qasim (son-in-law of Mir Jafar who had betrayed Siraj ud-Daulah during the Battle of Plassey) executed the Jagat Seth before raiding Patna which had been occupied by the British. He eventually lost the Battle of Buxar, and Barh and Patna were taken into the British Empire.