The last major extension of British Indian territory took place during the time of

The correct answer is Lord Dalhousie. His tenure as Governor-General (1848–1856) marked the last massive wave of territorial expansion of the British Empire within the Indian subcontinent.

Dalhousie expanded British control extensively through three main methods:

• Direct Conquest: Annexation of the Punjab (1849) after the Second Anglo-Sikh War, and Lower Burma (1852).
• Doctrine of Lapse: Annexation of several princely states, including Satara (1848), Sambalpur (1849), Jhansi (1853), and Nagpur (1854), by refusing to recognize adopted heirs.
• Misgovernance: The strategic and resource-rich state of Awadh was annexed in 1856 on charges of maladministration.

While Lord Dufferin later oversaw the annexation of Upper Burma in 1885, Dalhousie's sweeping acquisitions are historically recognized in Indian competitive exams as the last major territorial extension that defined the political map of British India.