The Battle of Plassey (1757) was decisively won by the British primarily due to the betrayal by Mir Jafar, the Commander-in-Chief of Siraj-ud-Daulah's army. Mir Jafar conspired with the British and deliberately withheld his forces from the battle. While Clive's leadership was important and French withdrawal helped, Mir Jafar's treachery was the decisive factor that turned the battle. This victory marked the beginning of British political dominance in Bengal.