He served with his regiment during the hard-fought war against
Hyder Ali (1780–1783), under his namesake Major Sir
Hector Munro, 8th of Novar. Thomas also later served alongside another namesake
John Munro, 9th of Teaninich. Thomas served again with his regiment in the first campaign against
Tipu Sultan (1790–1792). He was then chosen as one of four military officers to administer part of the territory captured from Tipu, where he remained for seven years learning the principles of revenue survey and assessment which he afterwards applied throughout the presidency of Madras. After the final downfall of Tipu in 1799, he spent a short time restoring order in
Kanara; and then for another seven years (1800–1807) he was placed in charge of the
Ceded Districts ceded by the
Nizam of
Hyderabad, where he introduced the
ryotwari system of land revenue. After a long furlough in
Britain, during which he gave valuable evidence upon matters connected with the renewal of the
East India Company's charter, he returned to Madras in 1814 with special instructions to reform the judicial and police systems. In response to a question put to him in 1813, concerning the renewal of the charter, he stated: I do not exactly know what is meant by civilizing the people of India. In the theory and practice of good government they may be deficient; but if a good system of agriculture, if unrivalled manufactures—if a capacity to produce what luxury or convenience demands—if the establishment of schools for reading and writing—if the general practice of kindness and hospitality—and, above all, if a scrupulous respect and delicacy towards the female sex, are amongst the points that denote civilized people, then the Hindoos are not inferior in civilization to the people of Europe. He was affectionately called 'mandrolayya' by local
Telugu people after he brokered peace between local
Polygars. On the outbreak of the
Pindari War in 1817, he was appointed as brigadier-general to command the reserve division formed to reduce the southern territories of the
Peshwa. Of his services on this occasion
Lord Canning said in the
House of Commons: In 1819, Munro was appointed a
Knight Commander of the Order of the Bath (KCB). ==Governor of Madras==