The title Earl of Mornington was created in the Peerage of Ireland in 1760 for Garret Wellesley. On the death of the fifth earl it passed to the dukedom of Wellington, where it has remained. The subsidiary titles associated with this peerage are Viscount Wellesley (1760) and Baron Mornington (1746), both in the Peerage of Ireland.
The second earl, Richard Wellesley, was created Baron Wellesley in the Peerage of Great Britain in 1797 and Marquess Wellesley in the Peerage of Ireland in 1799, which titles became extinct at his death. The third earl had been created Baron Maryborough in the Peerage of Ireland in 1821. This title became extinct on the death of his grandson the fifth earl.
Wellesley was educated at Eton from 1781 to 1785, but a lack of success there, combined with a shortage of family funds, led to a move to Brussels in Belgium to receive further education.
Wellesley was elected MP for Rye (in the British House of Commons) for six months in 1806; a year later, he was elected MP for Newport on the Isle of Wight, a constituency he would represent for two years.
Viscount Wellington, of Talavera and of Wellington in the County of Somerset (4 September 1809)