Napoleon's planned invasion of the United Kingdom
Napoleon's planned invasion of the United Kingdom at the start of the War of the Third Coalition, although never carried out, was a major influence on British naval strategy and the fortification of the coast of southeast England. French attempts to invade Ireland in order to destabilise the United Kingdom or as a stepping-stone to Great Britain had already occurred in 1796. The first French "Army of England" had gathered on the Channel coast in 1798, but an invasion of England was sidelined by Napoleon's concentration on campaigns in Egypt and against Austria, and shelved in 1802 by the Peace of Amiens. Building on planning for mooted invasions under France's Ancien Régime in 1744, 1759 and 1779, preparations began again in earnest soon after the outbreak of war in 1803, and were finally called off in 1805, before the Battle of Trafalgar.