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Birth date and place

The exact date and location of Wellesley's birth is not known, but biographers mostly follow the same contemporary newspaper evidence, which states that he was born on 1 May 1769, the day before he was baptised in St. Peter's Church on Aungier Street in Dublin. However, Ernest Lloyd states "registry of St. Peter's Church, Dublin, shows that he was christened there on 30 April 1769". His baptismal font was donated to St. Nahi's Church in Dundrum, Dublin, in 1914.

Wellesley may have been born at his parents' townhouse, Mornington House at 6 Merrion Street (the address later became known as 24 Upper Merrion Street), Dublin, which now forms part of the Merrion Hotel. His mother, Anne, Countess of Mornington, recalled in 1815 that he had been born at 6 Merrion Street.

His family's home at Dangan Castle, Dangan near Summerhill, County Meath has also been purported to have been his birthplace. In his obituary, published in The Times in 1852, it was reported that Dangan was unanimously believed to have been the place of his birth, though suggested it was unlikely, but not impossible, that the family had travelled to Dublin for his baptism. A pillar was erected in his honour near Dangan in 1817.

The place of his birth has been much disputed following his death, with Sir J.B. Burke writing the following in 1873:

"Isn't it remarkable that until recently all the old memoirs of the Duke of Wellington seemed to infer that County Meath was the place of birth. Nowadays the theory that he was born in Dublin is generally accepted but by no means proved".

Other places that have been put forward as the location of his birth include a coach between Meath and Dublin, the Dublin packet boat and the Wellesley townhouse in Trim, County Meath.