 St Nazaire is on the north bank of the Loire 400 km ( 250 miles ) from the nearest British port . In 1942 , it had a population of 50 @,@ 000 . The St Nazaire port has an outer harbour known as the Avant Port , formed by two piers <unk> out into the Atlantic Ocean . This leads to two lock gates before the Bassin de St Nazaire . These gates control the water level in the basin so that it is not affected by the tide . 
