Napoleon defeated Prince Gerbhard von Blücher’s Prussian army at Ligny on 16 June 1815, forcing it to retreat to Wavre. The battle of Quatre Bras between the French and the Duke of Wellington’s Allied army on the same day was a draw. Napoleon intended to outflank them the next day, but his slowness in acting allowed Wellington to pull back ‘to a ridge line south of Mont St Jean, a position that had been carefully noted by Wellington and his staff some time ago as being an excellent defensive position.’[1]

Source: “Waterloo Campaign map-alt3” by Ipankonin – Self-made. Vectorized from raster image Flags from. Licensed under CC BY-SA 3.0 via Wikimedia Commons – https://commons.wikimedia.org/wiki/File:Waterloo_Campaign_map-alt3.svg#/media/File:Waterloo_Campaign_map-alt3.svg

On 18 June the two armies at Waterloo faced each other on two low ridges that were separated by a gentle valley, which was bisected by the Charleroi to Brussels road. The frontage was…