After the First Burma War the Regiment was stationed in Assam as part of the new garrison and from 1826 to 1860 it saw much fighting with the many local tribes who resented the East India Company’s encroachment into their territories.
In 1827 there was another change of name and the Regiment became the Assam Light Infantry. In 1828 its establishment was increased to twelve companies, each to ninety-three men. The two new companies were composed entirely of Gurkhas, some of whom were already serving in the Regiment and some who transferred from other corps.
The Regiment marched to Jorhat in 1829 from where four companies were deployed to deal with the dissident Raja of Biba. In this year two British Officers and their escort were killed by some five hundred Khasiah tribesmen. The resulting operations against both the Khasiah and the Garo tribes, which involved both the Regiment and the Sylhet Light Infantry, lasted until 1832 before being successfully brought to and end.
In 1834 and 1835 the Singpho tribe became troublesome during the fighting which resulted in Regiment suffering a number of casualties before the tribesmen were defeated. 1835 saw yet another reorganisation when two companies were transferred to the Assam Subundy Corps, later to become the 8th Gurkha Rifles. This transfer left the Regiment with ten companies once again as it left Jorhat for Sadiya in 1839.
Up until this time the Regiment had not been commanded by any officer above the rank of Major but in 1839 the Commanding Officer, Major White, was promoted to Lieutenant Colonel. Shortly after his promotion he was killed together with the Subedar Major and a number of soldiers in a surprise attack on Sadiya by Kampti tribesmen. As a result of this the Kampti tribe was broken up and resettled in various parts of India.
Captain J F Hannay succeeded as Commanding Officer, a position he was to hold for the next twenty-two years! Hannay was the grandson of Simon Fraser. The descendents of these two officers continued to have close associations with the Regiment in later years.
In 1840 the artillery detachment was removed from the Regiment and transferred to the newly formed Assam Local Artillery. In 1843 a stockade in Bisa, garrisoned by a detachment of the Regiment, was besieged by the Singphos. When and food and water ran out the Garrison, under promise of safe conduct, surrendered and were then butchered by the tribesmen. The subsequent operations broke the power of the Singpho tribe for ever.
Having account for two tribes during its stay in Sadiya the Regiment moved to Jaipur in 1844 where it soon came to grips with the formidable Naga tribe, one of the largest and most warlike of all the tribes on the North East Frontier. 1844 bought yet another change of name, this time to the 1st Assam Light Infantry while the Assam Sebundy Corps became the 2nd Assam Light Infantry.
The Regiment left Jaipur for Dibrugarh in November 1847 but the battles with the Nagas continued. In 1849 a very gallant attack on a stockade held by the Nagas resulted in Sepoy Humail Khan being awarded the OBI. The years that followed found the Regiment fully occupied with skirmishes against the tribesmen in the area. An attack on the Mishmi tribe led by Lieutenant Eden was particularly successful. This officer along with twenty hand-picked men made an eight day forced march into the Mishmi hills, captured the chief at daybreak and brought him back to be tried and subsequently hanged. Two sepoys in this fighting patrol were awarded the IOM.