In 1732, he went to the rescue of Sardar Ala Singh who had been besieged in Barnala by Manjh and Bhatti Rajputs in collaboration with the faujdar of Jalandhar and the nawab of Malerkotla. In 1733, when the Mughal governor of Lahore sought peace with the Sikhs offering them a nawabship and a jagir, Baba Deep Singh and his jatha joined Nawab Kapur Singh at Amritsar to form a joint Sikh force, the Dal Khalsa, which was soon divided for administrative convenience into the Buddha Dal and the Taruna Dal, the latter being further split into five jathas. Deep Singh, now reverently called Baba, was given the command of one of these jathas which in 1748 were redesignated misls. It came to be known as Shahid misl. As the leader of the Shaheedi misl, he achieved numerous victories for the Sikhs. The Shahid misl had its sphere of influence south of the River Sutlej and Baba Deep Singh's headquarters remained at Talvandi Sabo. The tower in which he lived still stands next to the Takht Sri Damdama Sahib and is known as Burj Baba Deep Singh Shahid.

At the invitation of Mughlani Begum, Ahmed Shah Abdali invaded India for the fourth time during the years 1755-56. On his return journey Abdali was accompanied by his soldiers who carried enormous stores of gold, silver and other valuables looted from the towns of Mathura, Bindraban, Agra and Delhi. These valuables were loaded on the backs of horses and other animals. In addition thousands of beautiful unmarried girls and married women, from both Hindu and Muslim communities, were being forcibly taken against their wishes, to serve as maidens and slaves of Abdali, and to be auctioned in open market. They were herded together in bullock carts and bound to prevent their escape enroute.