In September, Grant was assigned to lead an advance party of around 800 men to determine the French strength at Fort Duquesne (the future site of Pittsburgh). The force was made up mainly of militia, but he took along a number of officers from the regulars since he had little respect for the colonial troops. He decided to split his force, hoping to encourage a French attack that he could surprise and overwhelm. Having no wilderness experience, he was ambushed himself by Indians and French on 14 September 1758. At this engagement, the Battle of Fort Duquesne, the British force was repelled with 342 men killed, wounded or captured. The prisoners consisted of Major Grant and 18 of his men. He was paroled soon after and tried to blame his defeat on the failure of the colonial militia to follow orders.