Before turning to political life, Hamilton served in the
British Army. He purchased a commission as
Ensign &
Lieutenant in the
Grenadier Guards on 27 May 1862, buying his promotion to Lieutenant &
Captain on 8 August 1865, before retiring by sale of his commission on 8 June 1867. On 10 July 1867 he was appointed
Lieutenant-Colonel Commandant of the part-time
Prince of Wales's Own Donegal Militia (later the 5th (Donegal Militia) Battalion, Royal Inniskilling Fusiliers) in succession to his uncle,
Lord Claud Hamilton (1813–1884). He was appointed
Honorary Colonel of the battalion on 17 January 1891, in succession to his elder brother
James Hamilton, 2nd Duke of Abercorn. In 1865, he became
Conservative MP for
Londonderry City until 1868 when he was appointed a
Lord of the Treasury in
Benjamin Disraeli's first ministry. In 1869, he became MP for
King's Lynn until 1880, for
Liverpool from 1880 to 1885, for
Liverpool West Derby from 1885 until he
resigned his seat in 1888, and for
Kensington South from
January 1910 to
1918. ==Personal life==