 Rapid improvements followed, notably under the leadership of the Marquis of Ensenada, and the position of Ferrol was made almost unassailable from the sea, the difficulties of disembarking troops on its precipitous coast being strengthened by a renewed line of fortresses and newly built castles, including that of San Carlos.The Royal Dockyards of A Graña and Ferrol (Reales Astilleros de Esteiro), built between 1726–1783, produced ships protected with copper sheets from the rolling mills of Xubia.In 1772, The Spanish Royal Academy of Naval Engineers of Ferrol, the first such academy in Spain, was created.