Trade maps reveal targets for economic warfare

The Royal Navy's trade map works in two directions: it shows both the merchant routes Britain had to defend and the economic arteries it could attack. British and Commonwealth vessels used routes serving other major powers, so the same network revealed potential pressure points in wars with Germany, Italy, Japan, or even the highly unlikely case of the United States. In a global trading system, dependence on shipping was a shared strategic vulnerability. The blockade of Germany demonstrates the offensive side of sea control, while German access to Norwegian iron ore shows how control of a particular supply route could affect industrial endurance. The map therefore doubles as a guide to blockade and maritime economic warfare.