Ajit Singh (1687–1704) also referred to with honorifics as Sahibzada Ajit Singh or Baba Ajit Singh was the eldest son of Sikh guru Guru Gobind Singh. His younger brothers were Sahibzada Jujhar Singh, Sahibzada Zorawar Singh and Sahibzada Fateh Singh. He was killed during Second Battle of Chamkaur
Ajit Singh was born to Mata Sundari and Guru Gobind Singh at Patna Sahib on 3 January 1687. The following year, Guru Gobind Singh returned with the family to Anandpur where Ajit Singh was brought up in the approved Sikh style. He was taught religious texts, philosophy and history, and had training in the arts such as riding, swordsmanship and archery,From Baba Jeevan Singh ji (Bhai Jaita Ji)
In 1691, Mata Sundari gave birth to another boy who was named Jujhar Singh. Sahibzada Jujhar Singh was four years younger than Ajit Singh. Sahibzada Ajit Singh became a model for him. Jujhar Singh also was entrusted with several engagements around Anandpur and on hills. Both Ajit Singh and Jujhar Singh led hundreds of successful expeditions, helping the needy who would come to Guru Gobind Singh asking to get them justice.
Second Battle of Chamkaur:
When Mughal forces besieged Anandpur in 1704, Sahibzada Ajit Singh again displayed his qualities of courage and steadfastness. After a long stalemate, the Mughal Faujdar gave his assurances that he only wanted the fort of Anandpur and would let the population of the town go unharmed. Anandpur was vacated on the night of 5th and 6 December 1704. Sahibzada Ajit Singh was given the command of the rearguard. As the besiegers, violating their solemn promises, attacked the column, he stoutly engaged them on a hill-feature called Shahi Tibbi until he was relieved by Bhai Udai Singh. Ajit Singh crossed the Sarsa rivulet, then in spate, along with his father, younger brother, Jujhar Singh, and some others. Further reduced in numbers by casualties at the hands of pursuing troops from Ropar, the column reached Kotla Nihanga and then proceeded to Chamkaur on the night between 6th and 7 December 1704. There they rested for some hours in the fortress of Budhi Chand Rawat. But, in the afternoon the Muslim soldiers from Malerkotla and Sirhind reached there, surrounded the fortress, and threw a tight ring around it. The Sikhs too took up position. An unequal but grim battle began. The Sikhs had exhausted the meagre stock of ammunitions and arrows, hence they made sallies in batches of five each to engage the encircling host with sword and spear.
Sahibzada Ajit Singh led one of the sallies and laid down his life fighting in the thick of the battle. Gurdwara Katalgarh now marks the spot where he fell, followed by Sahibzada Jhujhar Singh who led the next sally. An annual fair is held in the commemoration of their martyrdoms in December – January.
Ajitgarh, one of the largest cities in Punjab lying adjacent to its capital Chandigarh, has been named in the memory of Sahibzada Ajit Singh, Ajitgarh (‘Home of Ajit’). It is located in the district of the state which is also named after him Sahibzada Ajit Singh Nagar District.