Sardar Chet Singh Kahlon of Lahore taken by surprise when attacked by his own relation Maharaja Ranjit Singh.

Portrait of Sardar Gurbaksh Singh Kanhaiya, father-in-law of Maharaja Ranjit Singh. He was the son of Sardar Jai Singh Kanhaiya leader of the powerful Kanhaiya Misl which eventually proved to be the deciding factor in the contest between the Sukarchakia Misl and the Bhangi Misl for supremacy.

He was actually killed in a conflict with the Sukarchakia Misl then under the control of Ranjit’s father Mahan, but his far sighted widow Rani Sada Kaur decided to get her daughter betrothed to the young Ranjit which enabled the fortunes of the Kanhaiya and Sukarchakia Misls to be tied and to be able to defeat their competitor the Bhangi Misl. 

Rani Sada Kaur was instrumental to Ranjit Singh taking Lahore - I found this on a website on what she had to say to Sardar Chet Singh Kahlon, who had locked himself in the Lahore Fort having been caught by surprise as he was a relation of Ranjit (Lehna had died two years earlier in 1797).

“She said, “I want to see Chaet Singh.” 

“Who are you?” Chaet Singh’s emissary questioned. 

“I am Rani Sada Kaur from Batala. I want to meet with Chaet Singh for his own benefit.” 

The emissary left and returned after a short duration. He announced, “Sardar is only prepared to talk inside the fort.” 

“Doesn’t matter, I can come inside. To me, Chaet Singh is same as my son, Ranjit Singh.” Saying this Rani followed the emissary inside the fort. Chaet Singh was a distant relative too. 

Entering the fort, Sada Kaur immediately accesses the situation. In her assessment, the situation inside the fort was rapidly deteriorating. 

Upon meeting Chaet Singh, she said, “Biba! I have come for your sake. I don’t wish you any harm.” 

Chaet Singh was already concerned and her words further scared him. He didn’t know what disaster was awaiting him. 

“Ranjit Singh is entrenched with heavy canyons. With great difficult, I managed to convince him to stop firing. His fate is shining while his destiny is around the corner. All Sardars have accepted his conditions. You don’t have enough strength to face him. Consider, you may be killed.” Rani Sada Kaur explained. 

“If I am to die, then why not die like a brave solider?” Chaet Singh responded. 

“There is no need to die. After all you have children. If I desired death for you, why would I come this far? I have come to save you.” Sada Kaur answered. 

She repeated once again “Biba! Leave the fort. This will not only save you and your family’s life but I will take personal responsibility for your continued sustainment.” 

Sada Kaur’s words hit the right target. Chaet Singh agreed to leave the fort. After two hours, he accompanied Sada Kaur into Ranjit Singh’s tent and deposited the keys to the Lahore fort. As per her agreement, Rani Sada Kaur ensured that Chaet Singh got his Jagir in compensation. The fort was under Ranjit Singh’s control now while the Kesri flag fluttered over it. Without Sada Kaur’s brave and wise moves, the fort couldn’t have been captured so easily and that too in such a short time. Any delay could have been nothing less than disastrous, as the enemy forces were already on their way to get it released from his occupancy. Having captured the fort, Ranjit Singh now controlled Lahore. All gates to the city were ordered shut and the fort was reinforced with canyons and prepared to defend against any possible attack. In the meantime, news reached that Jodh Singh Ramgahria, Gulab Singh Bhangi, Sahib Singh Bhangi, Nijaam Deen Ksuriya and numerous other Sardars with heavy forces had camped in the fields of Baseen. They were awaiting additional reinforcements and planned to attack Lahore.”

https://www.allaboutsikhs.com/biographies/great-sikh-women/rani-sada-kaur/