Due to its position, Calais since the Middle Ages has been a major port and a very important centre for transport and trading with England. Calais came under English control after Edward III of England captured the city in 1347, followed by a treaty in 1360 that formally assigned Calais to English rule. Calais grew into a thriving centre for wool production, and came to be called the "brightest jewel in the English crown" owing to its great importance as the gateway for the tin, lead, lace and wool trades (or "staples"). Calais remained under English control until its capture by France in 1558. The town was virtually razed to the ground during World War II, when in May 1940, it was a strategic bombing target of the invading German forces who took the town during the siege of Calais. During World War II, the Germans built massive bunkers along the coast in preparation for launching missiles at England.