Commissioned an ensign in the 22nd Regiment of Foot on 16 April 1785, he was promoted to lieutenant in the 100th Regiment of Foot on 10 December 1785. On 27 May 1787, he was commissioned a lieutenant in the Somersetshire Regiment of Militia, and was promoted from captain-lieutenant to captain on 22 April 1789. On 27 January 1791, he was promoted captain in an independent company, from a lieutenancy in the 34th Regiment of Foot, and shortly thereafter exchanged into the 14th Regiment of Foot. On 5 April 1794, he was promoted to major in the recently-raised 87th Regiment of Foot, and was promoted to lieutenant-colonel in the regiment on 19 July. On 20 January 1795, he exchanged into the 11th Regiment of Foot. Dungarvan exchanged into the captaincy of a company in the Coldstream Guards on 21 May 1796, and was appointed an aide-de-camp to George III on 9 January 1798. On July 1803, he exchanged from the half-pay of the 4th Regiment of Foot to become colonel of a reserve battalion of infantry, the 16th Garrison Battalion. On 27 May 1825, he was breveted general. The Earl was appointed a Knight of the Order of St Patrick on 22 July 1835.
Personal life
On 9 October 1795, he married his first cousin Isabella Henrietta Poyntz, daughter of William Poyntz and his wife Isabella, daughter of Kelland Courtenay. Edmund and Isabella had nine children, :
In Somerset he lived at Marston House within the grounds of Marston Bigot Park. He employed Jeffry Wyattville in 1817 to embellish the central block with four Ionic columns. Wyattville was known locally for his work at Longleat and then at the Church of St John the Baptist, Frome in the same decade. In 1821, on the corner of the then named Hill Street and the Market Place in Frome, the Earl was persuaded by Thomas Bunn to build an Assembly Room above a covered market, in the style of the Greek revival; in 1822, the street was renamed Cork Street. He had been shown by Bunn an image of the Roman Forum as 'a good design for a modern market-place'; he had demurred and 'thought of economy and said it would not pay'. Bunn's persuasion paid off; it remains one of Frome's notable buildings, now a bank with the ground floor enclosed. They worked together on various other projects, including the National and Christ Church Schools, with the Earl as the chair of committee. The Earl contributed to local charities such as the Blanket Fund and the Coal Fund, both for the relief of the poor, and chaired meetings of the Frome Savings Bank. Thomas Bunn thought highly of him as 'a kind friend to the inhabitants of Frome'. In November 1838 he recorded an incident in the Magistrate's Court when, finding the room very crowded, the Earl took up his own coat from the bench beside him and offered Bunn a seat: 'not as a mark of attention to me but of gentlemanly conduct'. He died on 29 June 1856 and was succeeded by his grandson Richard. In 1857 his youngest son, Richard Boyle, vicar of Marston, had a school and schoolhouse built "For The Benefit of The Poor And In Memory of His father" on Tuckmarsh Lane along the south-east boundary of the family estate.
