Son of Basava Singh Sandhanvalia, was a leading actor in the gruesome drama of intrigue and murder enacted, in the Sikh kingdom following the passing away of Maharaja Ranjit Singh. One of the younger generation of the Sandhanvalias, he outstripped his uncles, Atar Singh Sandhanvalia and Lahina Singh Sandhanvalia, in political ambition and conspiracy. In 1840, on his return from the expedition against the Raja of Mandi, he joined his uncles in supporting Rani Chand Kaur's claim against Sher Singh. Fearful of the Dogra minister, Dhian Singh, who had supported Maharaja Sher Singh against Ran! Chand Kaur, Ajit Singh fled Lahore in January 1841 clandestinely, along with his jewellery, and arrived in Ludhiana to seek the help and protection of the British political agent. Meanwhile, his uncle Atar Singh also left Lahore and joined him in Ludhiana. At this, Sher Singh besieged the Sandhanvalia fortress at Raja Sansi and ordered that both Lahina Singh Sandhanvalia and his son, Kehar Singh Sandhanvalia, be detained in Kot Kangra. The Sandhanvalia refugees in the British territory now came out openly against Maharaja Sher Singh. They wrote letters inciting the officers of the Khalsa army to rise against him. Ajit Singh took the journey to Calcutta to plead with the British governor general the cause of Rani Chand Kaur. Eventually, obtaining Maharaja Sher Singh's pardon through the good offices of the British, Atar Singh and Ajit Singh returned to Lahore in May 1843. The unsuspecting Maharaja released Lahina Singh Sandhanvalia and Kehar Singh Sandhanvalia as well and restored all the confiscated Sandhanvalia fiefs. Ajit Singh and other Sandhanvalia sardars, however, nursed feelings of malice in secret and waited for their opportunity to strike. On 15 September 1843, as Maharaja Sher Singh was inspecting troops in the Baradari of Shah Bilaval, Ajit Singh shot him dead with an English rifle which he cunningly pretended to present to the Maharaja for inspection. As the Maharaja fell, Ajit Singh drew his sword and severed his head. The senior Sandhanvalia Lahina Singh murdered the Maharaja's minor son, Kanvar Partap Singh in a garden close by. Later, inside the Lahore Fort, while apportioning the office of prime minister among themselves, Ajit Singh killed Dhian Singh on the spot. Hira Singh, son of Dhian Singh, and his uncle, Suchet Singh, aroused a section of the army, and with General Avitabile's crack battalions, they besieged the Fort on 16 September 1843, and in the resultant action both Ajit Singh and Lahina Singh were slain. Their heads were cut off and bodies quartered and hung on the different gates of the city. At Raja Sans! the Sandhanvalia fort was razed to the ground, and the houses of all Sandhanvalia chiefs were destroyed. It was then ordered that henceforth all Sandhanvalia lands be ploughed with asses instead of oxen. The only Sandhanvalia chief to escape retribution was Atar Singh who fled from Una to the British territory.