He was engaged in the First Anglo-Sikh War, and the 10th Regiment was one of those that were called up to help to fill the gap caused by the heavy losses at Mudkí and Firozshah.

Thereupon he refused to go return to the United Kingdom of Great Britain and Ireland, and remained at Calcutta until his health was sufficiently restored to enable him to take the field.

Franks was then to meet Sir Jung Bahadur Rana, the prime minister of Nepal, who had promised to bring a force of Goorkhas to the assistance of the British.

This programme was successfully carried out; on 19 and 23 February Franks inflicted defeats on the rebel leader, Muhammad Hussein Nazim, at Chanda, and between Badshahganj and Sultánpur.

The effect of these victories, in which Franks lost only two men killed and sixteen wounded, was, however, reduced by the severe check that he received in an attempt to take Dohrighat.

He authored and had printed by Spottiswoode & Co. a pamphlet, "for private circulation" in England, collecting his despatches of the 1857–58 Indian Rebellion during his early 1858 campaign in through modern Uttar Pradesh, from Benares (Varanasi) in the then North-Western Provinces to Lucknow in Oudh.