Passage: In the 17th century, the English East India Company had been given a grant of the town of Calcutta by the Mughal Prince Shah Shuja. At this time the Company was effectively another tributary power of the Mughal. During the following century, the company obtained sole trading rights for the province and went on to become the dominant power in Bengal. In 1757, at the Battle of Plassey, the British defeated the nawab Siraj Ud Daulah and plundered the Bengali treasury. In 1764 their military control was reaffirmed at Buxar. The subsequent treaty gained them the diwani, that is, taxation rights; the Company thereby became the de facto ruler of Bengal.

Question: What year was the military control reaffirmed at?
1764