 Complete the following phrase:  In fact the logical place to assemble 800 or so ships was in the large lagoon where now there is farmland and a maze of drainage ditches behind a coastal fringe of islands where the modern ports of Calais and Dunkirk now sit because in Caesars day an estuary stretched all the way inland to the site of the modern town Saint-Omer. In 1944, French historian Albert Grenier, against the backdrop of 