 A bridge on the west (landward) side provided the only access route.By the late 1850s, Britain and France were locked in an arms race.A new generation of increasingly accurate and powerful guns had been developed (of the rifled muzzle loader (RML) and rifled breech loader (RBL) types), mounted on fast-moving, manoueuvrable steam-powered ironclad warships such as the French "La Gloire" and the British .