The Company was very keen to have a puppet ruler in place of Sirajuddaulah so that it might enjoy trade concessions and other privileges. It began to help one of Sirajuddaulah’s rivals become the nawab. This infuriated Sirajuddaulah. He sternly asked the Company to stop meddling in the political affairs of his dominion. After negotiations failed, the Nawab marched with his soldiers to the English factory at Kasimbazar, captured the Company officials, disarmed all Englishmen, and blocked English ships. Then he marched to Calcutta to establish control over the Company’s fort there. As soon as the Company officials in Madras heard the news of the fall of Calcutta, they sent forces under the command of Robert Clive, reinforced by naval fleets. Prolonged negotiations with the Nawab followed. But no concrete solution came out. Finally, in 1759, Robert Clive led the Company’s army against Sirajuddaulah at Plassey.

In this battle, Sirajuddaulah got defeated. The main reason was that one of his commanders, Mir Jafar, did not fight the battle. He, in fact, supported the Company by not fighting because the Company had promised to make him Nawab after defeating Sirajuddaulah. The victory of the Company in the Battle of Plassey gave it immense confidence. It was the first major victory of the Company in India.