he Battle of Plassey, 23 June 1757, was a decisive British East India
Company victory over the Nawab of Bengal and his French allies,
establishing Company rule in South Asia which expanded over much of the
Indies for the next 190 years. The battle took place at Palashi, Bengal,
on the river banks of the Bhagirathi River, about 150 km north of
Calcutta, near Murshidabad, then capital of undivided Bengal. The
belligerents were Siraj-ud-daulah, the last independent Nawab of Bengal,
and the British East India Company.

More info: http://en.wikipedia.org/wiki/Battle_of_Plassey

The head of the military was called the Mir Bakshi, appointed from among
the leading nobles of the court. The Mir Bakshi was in charge of
intelligence gathering, and also made recommendations to the emperor for
military appointments and promotions.