Channel Ports The Channel Ports are seaports in southern England and the facing continent , which allow for short crossings of the English Channel . There is no formal definition , but there is a general understanding of the term . Some ferry companies divide their routes into " short " and " long " crossings . The broadest definition might be from Plymouth east to Kent and from Roscoff to Zeebrugge although a tighter definition would exclude ports west of Newhaven and Dieppe . A historic group of such ports is the Cinque Ports of south - east England , most of which have ceased to be commercial ports . Ports . England . The ports vary in size and their relative importance has fluctuated during recent history . Dover has established a lead in the cross - Channel ferry routes through its geographic position and development of its facilities and hinterland . This business has been sustained despite competition from the Channel Tunnel . Other minor ports in Kent and Sussex have retained some trade but these tend to be single routes , such as Folkestone – Calais , Newhaven – Dieppe and Ramsgate – Ostend . Longer routes mainly radiate from Portsmouth but there are lesser ports at Poole , Weymouth and Plymouth with routes to Normandy , Brittany and Spain . France . The major French port with cross - Channel connections is Calais , principally with Dover but also with Folkestone . Other close French channel include Dunkirk , Boulogne and Dieppe . Longer routes are served from Le Havre , Caen , Cherbourg , Roscoff and St Malo . There are services to Ireland ( Rosslare and Cobh ) . Belgium . Ostend and Zeebrugge qualify as Channel ports , although Zeebrugge ' s current regular ferry links are with northern England and Scotland , outside this article ' s scope . Strategic importance . The ports are important commercial facilities , reinforcing connections between the British and European road systems . They are also vulnerable to industrial action such as strikes by port employees or blockade s by disgruntled fishermen . Their importance as military facilities was demonstrated during two World Wars . World War I . During World War I the British and French Channel ports were major conduits for British materiel and troops . The Belgian ports of Ostend and Zeebrugge were considered a major threat by British Admiral Admiral Jellicoe . He was concerned by their use not only as German U - boat ports , but also as torpedo boat bases and even possible departure points for a cross - Channel attack . This concern was transmitted via Whitehall to the British chief of staff on the Western Front , General Haig , for whom it merely confirmed the need for an offensive in Flanders , and eventually led to the Battle of Passchendaele ( also known as the Third Battle of Ypres ) . World War II . During World War II , likewise , they provided major supply routes which had to be reopened in 1944 . Dunkirk and Calais were the routes from which British and allied troops were evacuated in 1940 . In September , 1944 , the First Canadian Army ( at the time a blend of Canadian , British , Polish , Czechoslovak and other national units ) was tasked with capturing the ports from Le Havre to Zeebrugge . Dieppe and Ostende were undefended , but Le Havre , Boulogne and Calais required major military actions . It took several weeks to bring the ports back into use at a time when Allied armies badly needed supplies . Dunkirk was left under siege until the general German surrender .