A combination of Mughals and hillmen besieged Anandpur Sahib on the orders of emperor Aurangzeb. Finally the stock of food in the town ran out. The Mughals promised safe passage to Punjab for the Sikhs if they would hand over the fortress of Anandpur. At first Guru Gobind tested their promise of safe passage by staging a test which the attackers failed miserably. Later, with promises written in the margins of the Muslims' Holy Qur'an and some of the sacred writings of the Hindu elements of the army that had all but starved his small contingent of family and Sikhs and a personal promise of safety by Aurangzeb sent by an agent of the Emperor who was fighting in the distant Deccan, the Guru was persuaded to agree to their offer, leaving Anandpur with his family and a small band of retainers. During the flight from Anandpur when the Sikhs were promised safe passage to Punjab, Sahibzada Fateh Singh was, with his elder brother Zorawar Singh, put under the care of his grandmother, Mata Gujari Kaur ji. Unfortunately in the confusion of the rain-swollen Sarsa (normally little more than a creek) and an attack by Muslim pursuers, the Guru's two youngest sons and their grandmother were separated from the main body of Sikhs. Managing to get across, they were befriended by one of the Guru's former cooks. Later betrayed and handed off by the authorities of the small village where they had been given sanctuary, they were handed over to agents of Wazir Khan, carted off to Sirhind, and placed under arrest in the Khan's Thanda Burj (cold tower). The Thanda Burj was built to capture the cool night breezes of air drawn over water channels in the hot summers, during the dead of winter the unheated burj offered no comfort for the Guru's mother and sons.