AJĪT SIṄGH SANDHĀṄVĀLĪĀ (d. 1843), son of Basāvā Siṅgh Sandhāṅvālīā, was a leading actor in the gruesome drama of intrigue and murder enacted in the Sikh kingdom following the passing away of Mahārājā Raṇjīt Siṅgh. One of the younger generations of the Sandhāṅvālīās, he outstripped his uncles, Atar Siṅgh Sandhāṅvālīā and Lahiṇā Siṅgh Sandhāṅvālīā, in political ambition and conspiracy. In 1840, on his return from the expedition against the Rājā of Maṇḍī, he joined his uncles in supporting Rāṇī Chand Kaur's claim against Sher Siṅgh. Fearful of the Ḍogrā minister, Dhiān Siṅgh, who had supported Mahārājā Sher Siṅgh against Rāṇī Chand Kaur; Ajīt Siṅgh fled Lahore in January 1841 clandestinely, along with his jewellery, and arrived in Ludhiāṇā to seek the help and protection of the British political agent. Meanwhile, his uncle Atar Siṅgh also left Lahore and joined him in Ludhiāṇā. At this, Sher Siṅgh besieged the Sandhāṅvālīā fortress at Rājā Sāṅsī and ordered that both Lahiṇā Siṅgh Sandhāṅvālīā and his son, Kehar Siṅgh Sandhāṅvālīā, be detained in Koṭ Kāṅgṛā.

        The Sandhāṅvālīā refugees in the British territory now came out openly against Mahārājā Sher Siṅgh. They wrote letters inciting the officers of the Khālsā army to rise against him. Ajīt Siṅgh took the journey to Calcutta to plead with the British governor-general the cause of Rāṇī Chand Kaur. Eventually, obtaining Mahārājā Sher Siṅgh's pardon through the good offices of the British, Atar Siṅgh and Ajīt Siṅgh returned to Lahore in May 1843. The unsuspecting Mahārājā released Lahiṇā Siṅgh Sandhāṅvālīā and Kehar Siṅgh Sandhāṅvālīā as well and restored all the confiscated Sandhāṅvālīā fiefs. Ajīt Siṅgh and other Sandhāṅvālīā sardārs, however, nursed feelings of malice in secret and waited for their opportunity to strike. On 15 September 1843, as Mahārājā Sher Siṅgh was inspecting troops in the Bārādarī of Shāh Bilāval, Ajīt Siṅgh shot him dead with an English rifle which he cunningly pretended to present to the Mahārājā for inspection. As the Mahārājā fell, Ajīt Siṅgh drew his sword and severed his head. The senior Sandhāṅvālīā Lahiṇā Siṅgh murdered, in a garden close by, the Mahārājā's minor son, Kaṅvar Partāp Siṅgh. Later, inside the Lahore Fort, while apportioning the office of prime minister among themselves, Ajīt Siṅgh killed Dhiān Siṅgh on the spot. Hīrā Siṅgh, son of Dhiān Siṅgh, and his uncle, Suchet Siṅgh, 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 Ajīt Siṅgh and Lahiṇā Siṅgh were slain. Their heads were cut off and bodies quartered and hung on the different gates of the city. At Rājā Sāṅsī the Sandhāṅvālīā fort was razed to the ground, and the houses of all Sandhāṅvālīā chiefs were destroyed. It was then ordered that henceforth all Sandhāṅvālīā lands be ploughed with asses instead of oxen. The only Sandhāṅvālīā chief to escape retribution was Atar Siṅgh who fled from Ūnā to the British territory.