He was educated at Eton College, and was styled Lord Herbert until he succeeded to his father's earldom in 1749. He became a Lieutenant-General in the Army, later Colonel of the 1st Regiment of Dragoons. He became an authority on breaking cavalry horses and in 1755 built an indoor Riding School at Wilton House and commissioned 55 paintings of military riding exercises which now hang in the Large Smoking Room at Wilton. In 1756 he married the 19-year-old Lady Elizabeth Spencer, a daughter of Charles Spencer, 3rd Duke of Marlborough by his wife Elizabeth Trevor. As his London townhouse he purchased 40 Queen Anne St, Marylebone which he used for entertaining during the "London season". This must have been before 1760, as early that year he was despatched with his regiment to Germany to take part in the Seven Years' War as a Major-General in command of the Cavalry Brigade in Germany until the following year. In 1761 he wrote the British Army's manual on riding, Military Equitation: or A Method of Breaking Horses, and Teaching Soldiers to Ride, which had already reached a 4th edition by 1793, and his methods were adopted throughout the British cavalry. Henry was appointed a Lord of the Bedchamber to George III in 1769, and advanced to the rank of General in 1782.
George Augustus Herbert, 11th Earl of Pembroke, 8th Earl of Montgomery, son and heir, who married firstly in 1787, Elizabeth Beauclerk and secondly in 1808 Countess Catherine Romanovitch.
Charlotte Herbert, who died from consumption at age 10.
Mistresses
He had several mistresses amongst whom were:
Kitty Hunter, whom he met on his return to England in January 1762, and, disguised as a sailor, eloped with to the Low Countries having left a note for his wife. Horace Walpole commented:
On Henry's recall to the Army in Germany, the pregnant Kitty returned to England and on 23 November 1762 gave birth to their child Augustus Retnuh Reebkomp whose middle name spelled "Hunter" backwards and whose surname was an anagram of "Pembroke". He later adopted the surname "Montgomery". Henry returned to England in February 1763 and was reconciled to his wife in March.
Second mistress, with whom Henry had another affair in Venice in 1768, apparently carrying the lady off on the very night of her wedding to someone else. She gave birth to their illegitimate child Caroline Medkaff that year or the next.
