Wellington rose at around 02:00 or 03:00 on 18 June, and wrote letters until dawn. He had earlier written to Blücher confirming that he would give battle at Mont-Saint-Jean if Blücher could provide him with at least one corps; otherwise he would retreat towards Brussels. At a late-night council, Blücher's chief of staff, August Neidhardt von Gneisenau, had been distrustful of Wellington's strategy, but Blücher persuaded him that they should march to join Wellington's army. In the morning Wellington duly received a reply from Blücher, promising to support him with three corps.