The British annexed the then Assam into the Indian British Empire in 1826. After1826 the Lower Assam and the Central Assam (Darrang, Nagaon and Raha) were made one division which extended up to Biswanath. The division was placed under one Administrative Officer designated as the Principal Assistant to the Commissioner. The Upper Assam portion was left to the native rulers with supervisory control under a British political agent with political headquarters at Biswanath. Captain Neufville was the political agent for Upper Assam. Darrang Division was administered till 1833 from Guwahati.
Darrang was converted into a district and Mangaldai was made the district Headquarter in 1833. But due to various reasons the British shifted the head quarter to Tezpur in 1835. The district comprised of two sub-divisions, Tezpur sadar sub-division and Mangaldoi sub-division with head quarter at Mangaldoi. The District of Darrang was divided in to six Revenue Circles under one Sub-Deputy Collector in each Circle. There was one Transferred area in the district at Charduar. An Asstt. Political Officer was posted at Charduar under the Deputy Commissioner who acted as Political Officer.
Tezpur was a small township then. The British developed Tezpur as a small garrison township. Later, tea gardens were set-up throughout the district. The old steamarghat at Jahajghat, the Dak-Bungalow, the then Chummery compound at present Don-Bosco School campus, the Planters Club of Tezpur (Stations Club) , the Jahajghat Railway Station, the Church of Ephiphany etc and many tea gardens are some of the examples of the contributions of the British.