Hartopp was the son of the politician Edward Bourchier Hartopp and his wife, Honoria Gent. He was educated at Eton College. From Eton he enlisted with the 1st The Royal Dragoons, purchasing the rank of cornet in March 1853. Aged just eighteen, he served in the Crimean War and took part in the Charge of the Heavy Brigade at Balaclava in October 1854, during which he was severely wounded in the leg. He was promoted to the rank of lieutenant in December 1854, while from August 1855 he served with the Royal Horse Guards. He made a single appearance in first-class cricket for the Gentlemen of England against the Gentlemen of Kent and Sussex at Canterbury in 1857. Batting twice in the match, he was dismissed in the Gentlemen of England first-innings for a single run by South Norton, while in their second-innings he was dismissed for 5 runs by James Watts. He purchased the rank of captain with the Royal Horse Guards in April 1859, before retiring from active service in August 1871.