Their title originated from Duke Frederick William, who claimed the Duchy of Brunswick-Lüneburg, which the French had abolished in order to incorporate its lands into the French satellite Kingdom of Westphalia. The Black Brunswickers earned themselves a fearsome reputation over the following decade, taking part in several significant battles including the pre-Waterloo engagement at Quatre Bras on 16 June 1815, where the Duke lost his life. However, recruiting, the replacement of casualties, and finance had always been problematic, and the corps was disbanded in the early 1820s.