Mir Mannu became the new governor of Lahore and Multan on the 9th April 1748 A.D. He appointed Kaura Mal as his new Diwan. After setting right the administration of his province, he deployed army patrol to finish the Sikhs of his province. The Sikhs left his territory and moved to other states. Sardar Jassa singh Ramgarhia and his squad joined the army of the Commander of Jalandhar. The Sikhs gathered at Amritsar on the occasion of Diwali in 1748 A.D. When Mir Mannu came to know of the gathering of Sikhs, he sent his general with an army to blockade Amritsar and sent words to the Commander of Jalandhar, Adina beg to to take his army to help his general in finishing the Sikhs. Five hundred Singhs took shelter in fort of Ram Rauni and the rest moved to forests.
The combined forces of Lahore and Jalandhar surrounded the fort. The Singhs inside the fort did not surrender even after two months of siege. Sardar Jassa Singh Ramgarhia was in army who was in siege of fort, with his squad. One day he deserted the royal army and joined the Singhs inside the fort with his squad. The commander of Jalandhar felt the departure of the Singhs in this manner very much but could not do anything. Hearing the news of the second invasion of Abdali, Mir Mannu made peace with Sikhs and sanctioned an estate in Patti area for the livelihood.
During the third invasion of Abdali, one day in December, 1751 A.D, when the party of Sardar Sukha Singh was returning to his camp in the evening after a fight with a detachment of Abdali's troops, the artillery of Lahore made the party a target of their gun-shells. In this third invasion of Abdali all the Punjabis under Mir Mannu were together to face him. But when Mir Mannu's army of Lahore started attacking Dal Khalsa, the army of Dal Khalsa left the company of Mir Mannu after this mishap. The commander of Jalandhar got Kaura Mall murdered at the hands of a Pathan on the 6th March 1752 A.D. that resulted in Mir Mannu's defeat in the battle. Mir Mannu held the desertion of Dal Khalsa responsible for his defeat. He again plan to finish the Sikhs of his province.
Mir Mannu confiscated the estate of the Sikhs and deployed army patrols to eliminate them. He announced a reward of rupees ten for a person who brought a Singh's head. He also began to reward the informers for giving whereabouts of Singhs and their families. People in greed were getting Singhs and their families arrested.
They were brought to Lahore where Singhs were beheaded and their families were put in jails. Every woman was given forty pounds of grain to grind for each day in jail. A very heavy stone was placed on the chest of one who could not grind. Their children were transfixed on javelins before their very eyes. Their children were cut into pieces and garlands of those pieces were put around their mother's necks. They were given a quarter of bread to eat and a bowl of water in the whole day. Bowing to the will of God, those tolerated it all. On the 4th November, 1753 A.D., Mir Mannu died. After his death, Singhs set the prisoners free and took them away.