<P> Another significant challenge to British domination of the seas came during the Napoleonic Wars . The Battle of Trafalgar took place off the coast of Spain against a combined French and Spanish fleet and was won by Admiral Horatio Nelson, ending Napoleon's plans for a cross-Channel invasion and securing British dominance of the seas for over a century . </P> <P> The exceptional strategic importance of the Channel as a tool for blockade was recognised by the First Sea Lord Admiral Fisher in the years before World War I. "Five keys lock up the world! Singapore, the Cape, Alexandria, Gibraltar, Dover ." However, on 25 July 1909 Louis Blériot made the first Channel crossing from Calais to Dover in an aeroplane . Blériot's crossing signalled the end of the Channel as a barrier - moat for England against foreign enemies . </P> <P> Because the Kaiserliche Marine surface fleet could not match the British Grand Fleet, the Germans developed submarine warfare, which was to become a far greater threat to Britain . The Dover Patrol was set up just before the war started to escort cross-Channel troopships and to prevent submarines from sailing in the Channel, obliging them to travel to the Atlantic via the much longer route around Scotland . </P> <P> On land, the German army attempted to capture Channel ports in the Race to the Sea but although the trenches are often said to have stretched "from the frontier of Switzerland to the English Channel", they reached the coast at the North Sea . Much of the British war effort in Flanders was a bloody but successful strategy to prevent the Germans reaching the Channel coast . </P>

Where does the english channel meet the north sea