In 1835 Lord Auckland took up the appointment of Governor-General of India. As a legislator he dedicated himself especially to the improvement of native schools and the expansion of the commercial industry of India. But complications in Afghanistan interrupted this work in 1838.
Lord Auckland decided on war, and on October 1, 1838 in Simla published a manifesto dethroning Dost Mahommed Khan. After successful early operations he received promotion to the new title of Earl of Auckland. However the Afghan campaign ultimately ended in disaster (see Dost Mohammad and the British in Afghanistan for details of the first Anglo-Afghan war).
He handed over the governor-generalship to Lord Ellenborough and returned to England the following year. In 1846 he again became First Lord of the Admiralty, holding this office until his death on January 1, 1849.