This book deals with the importance of attacks by naval forces on international maritime trade and the subsequent effects on world politics. It covers five centuries and discusses the strategic value of naval action in the sphere of trade. Part I covers the period before the First World War. Part II deals with the 20th century including: naval blockades during the two World Wars; trade wars since 1945; the Falklands War and the 1990 Gulf War. There is an extensive bibliography and detailed index.