Kennedy is educated at Foyle College, Derry, and the Royal Military Academy, Woolwich, becoming lieutenant in the Royal Engineers in 1815. Four years afterwards, he is sent to Malta, and thence to Corfu. He superintends the construction of a canal at Lefkada in 1820, serves next under Sir Charles James Napier at Cephalonia building lighthouses, roads, and quays, and is sub-inspector of militia in the Ionian Islands (1828–31).
During a period in India Kennedy meets Sir Charles James Napier and when he returns to Ireland he sets up agricultural schools designed to improve the economy of the country. One is at Cloghan near Ballybofey, and another at Eglinton near Derry. He becomes a farm manager and marries Anna, daughter of Sir Charles Styles, who owns large estates around Ballybofey, in 1838. Kennedy′s methods of improving the condition of the agricultural classes are indicated by the title of his work, Instruct; Employ; Don’t Hang Them: or Ireland Tranquilized without Soldiers and Enriched without English Capital (1835). He writes several others of similar nature, and as inspector general for Irish education (1837), as secretary to the Devon Commission (1843), and to the Famine Relief Committee (1845), his labours are unceasing in behalf of his native land.
Kennedy returns to the army in 1849 as military secretary to Sir Charles Napier and accompanies him to India, where he builds the military road named after him and extending from Kalka via Shimla to Kunawur and Tibet. He publishes British Home and Colonial Empire (1865–69), as well as a number of technical works relating to his Indian career. He also serves as District Grandmaster of Bengal.
(Pictured: John Pitt Kennedy gravesite in Highgate Cemetery, London)