Pétiet, "Souvenirs militaires," p. 195.
Credit is primarily due to Constant de Rebecque, a Belgian, chief of staff to the Prince of Orange, for altering the point of concentration from Nivelles, as ordered by Wellington, to Quatre Bras; also to General Perponcher for supporting the new movement. The Belgian side of the campaign has been well set forth by Boulger in "The Belgians at Waterloo" (1901).
Gourgaud, "Campagne de 1815," ch. iv.