The corps system allowed Napoleon to turn his entire army 90 degrees to the right once over the Rhine. The manoeuvre was described by Ségur as ‘the greatest change of front ever known’ and meant that by October 6 the Grande Armée was in a line facing south, all the way from Ulm up to Ingolstadt on the Danube.56 This agile placing of a very large army across Mack’s line of retreat before he even knew what was happening, at the loss of no troops, stands as one of Napoleon’s most impressive military achievements.
