Final answer:
The Sikhs were forced to evacuate Sadhaura and Lohgarh and take refuge in the Jammu hills in December, 1720 A.D., marking a significant event in the history of Sikh resistance to Mughal persecution.
Step-by-step explanation:
The Sikhs were forced to evacuate Sadhaura and Lohgarh and take refuge in the Jammu hills in December, 1720 A.D. This event is a part of the larger historical context involving the persecution of Sikhs by the Mughal Empire. The execution of Guru Tegh Bahadur by Emperor Aurangzeb galvanized the Sikhs to resist Mughal authority more fervently. Such events are key to understanding the turbulent relationship between the Mughal rulers and the Sikh community, as well as the challenging circumstances the Sikhs faced during this period.