During the Middle Ages, Saint Malo was a fortified island at the mouth of the Rance River, Located between France and Brittany, Saint-Malo was a stake for both authorities. Although the town received its name from a Welsh monk called Mac Low,  the town was definitely linked to the kingdom of France in 1493.

In 1590, the inhabitants seized the castle the King of France, Henry IV. For four years they proclaimed their own "Republic", during which the motto of the corsair city was "Ni Français, ni Breton, Malouin suis " (Neither from France, Neither from Brittany, but from St Malo".
 
The  XVIIth  and XVIIIth centuries were the cornerstones of the port activities. The town got richer trading with the Indies, China, Africa and the Americas. During this period, Siméon de Garangeau designed a plan to built several forts off the coast and extended the town and its ramparts. These fortifications contributed to the English landing failing in 1758 during the 7-year war. Saint-Malo became a renown sea resort.