Which prince's wounding does the Lion's Mound commemorate?

The Lion's Mound commemorates the wounding of Prince William of Orange.

William, Prince of Orange, was the elder son of King William I of the Netherlands and served as a senior Allied commander during the Waterloo campaign. On 18 June 1815, a musket ball struck his shoulder and knocked him from his horse. The Lion's Mound marks the location traditionally associated with that injury.

William later became King William II of the Netherlands, which creates a frequent source of confusion in descriptions of the monument. At the time of Waterloo he was still the Prince of Orange, so that is the historically appropriate answer to the question.

The mound also commemorates the wider Allied victory and is connected with the nearby Battle of Quatre Bras, fought two days earlier. Its designer, Charles Vander Straeten, used the monumental lion to express victory and strength rather than creating a simple statue of the wounded prince.