Dover, Strait of, separating Great Britain from France and connecting the English Channel with the North Sea. It is 21 mi (34 km) wide between Dover and Cape Gris-Nez, near Calais, and is called Pas-de-Calais by the French. It is traversed regularly by ferry, hovercraft, and, with the completion of the Channel Tunnel, by rail. The Romans called it Fretum Gallicum. The Strait of Dover has been the scene of naval battles: in the 13th cent. Hubert de Burgh defeated the invading French, and in 1588 the Spanish Armada was checked there by the English.