The purpose of the Legion was to align the Irish hearts to the French cause in the imminent invasion of Ireland. General Pierre Augereau had been ordained to lead the invasion, and wanted Irishmen to serve in his army. However, the Battle of Cape Finisterre and the Battle of Trafalgar in 1805 made a safe sea crossing uncertain at best, and Napoleon was forced to abandon his plans for Ireland. He shifted his focus towards Austria and Eastern Europe and launched the Austerlitz campaign in late 1805. The legion remained on the French coast on garrison duty and coastal defence.