It was conferred by King Ferdinand VII on the British General Arthur Wellesley, then 1st Viscount Wellington, later 1st Duke of Wellington, in 1812, after his important victory at the Siege of Ciudad Rodrigo that same year, as a victory title.

In 1943, Anne Rhys (née Wellesley), the only daughter and eldest child of Arthur Wellesley, 5th Duke of Wellington, inherited the Spanish dukedom but not the British titles of her family, which passed to her uncle Gerald Wellesley, 7th Duke of Wellington after her younger brother was killed in action during the Second World War.

[2] King Juan Carlos of Spain, through his minister, granted the succession of the dukedom to the Marquess of Douro by Royal Decree of 21 May 2010.

As of 2024[update] the heir apparent to the Dukedom of Ciudad Rodrigo is the 10th Duke's eldest child, Arthur Wellesley, Earl of Mornington.

Lady Mae Madeleine is Lord Mornington's heir apparent to the Spanish dukedom as the eldest child, while Viscount Wellesley is the heir to the British dukedom as the eldest male, which could lead to another separation of these titles.