The Peninsular War’s maritime supply system

The difficult roads and mountains of the Iberian Peninsula made large overland supply trains vulnerable and slow. British control of the sea instead enabled convoys to move supplies and reinforcements to useful ports while avoiding the worst land routes. In Wellington's quoted order, ships at Corunna carry biscuit, flour, heavy artillery, and musket ammunition. He asks naval officers to convoy them to Santander and wait offshore if the enemy still holds the port until his army forces it to withdraw. The navy also helped return sick and wounded officers to Britain and bring experienced personnel back toward the fighting more quickly than an overland system could manage.