The duel came about because of religious differences between the Duke of Wellington and the 9th Earl of Winchilsea, George Finch-Hatton. Winchilsea had denounced Wellington’s support for Catholic emancipation. He accused the Duke of using his role in founding King’s as a way of hiding the ‘introduction of popery’ into the country (although founded as an Anglican institution, King’s was intending to award degrees to Catholics and other non-Anglicans). Wellington promptly challenged him to single combat to defend his honour and the College’s name.
The two men, accompanied by their seconds and a physician, met on the asparagus fields that would later become Battersea Park (on the south bank of the River Thames opposite Chelsea). As reported in The Guardian at the time: ‘The Duke of Wellington and Lord Winchilsea met at the appointed place. The parties having taken their ground, Lord Winchilsea received the Duke of Wellington's fire [he is believed to have deliberately aimed wide] and fired in the air.’
A written apology from Winchelsea was then enough to resolve the matter and a royal charter granted by George IV in August that year established King’s as a legal entity. Two years later, in October 1831, the college opened its doors to students for the first time.
King’s alumni all over the world have since commemorated Wellington’s role in the founding of King’s by gathering for social occasions on Duel Day and sometimes even re-enacting the duel itself.