Son of David Ochterlony, was born at Boston, Massachusetts, on 12 February 1758. In 1777, he joined the service of the East India Company as a cadet. He served under Lord Lake in the battle of Delhi and was appointed British resident in 1803 at the court of Shah 'Alam, emperor of Hindustan. In 1808, he was the garrison commander at Allahabad when he was ordered to advance to the Sutlej with a detachment to meet the Sikh troops in the Sutlej region. From 1809-14 he was agent to the GovernorGeneral at the Ludhiana Political Agency. As Resident at Delhi, he implemented the broad principles of Lord Wellesley's earlier policy towards Maharaja Ranjit Singh and the cisSutlej Sikhs, which aimed at establishing friendly relations with them and weaning them from Maratha influence. He remained active during the Sikh disturbances in the region (1804-05) and recommended to his government to take the Sikh chiefs under its protection.

In 1809, Ochterlony compiled his wellknown Report on the Sikh Country which furnished a first-hand statement on the power, revenue and military resources of the cisSutlej Sikhs. It referred to the conquests and grants of Ranjit Singh during his three Malva campaigns and to the ways and means to curtail Ranjit Singh's influence in the cisSutlej region. The Report enunciated the broad principles of paramountcy and protection offered to protected chiefs.

Ochterlony possessed considerable experience of Sikh affairs. But he often overestimated his authority, and failed to establish with the Sikh government the amicability enjoined upon by the treaty of Amritsar. His despatches from Ludhiana exhibited an unreasonable obsession on his part with what he called Ranjit Singh's schemes of expansion.

Ochterlony was promoted colonel in January 1812 and in June 1814 he was made major-general. He served in the Nepal war (1814-16) and the Pindari war (1817-18). In 1818, he was appointed Resident in Rajputana. In 1825, he resigned owing to differences with Lord Amherst on the Bharatpur succession issue. He died on 15 July 1825.