In this episode we discover that there was only one major clash of fleets in World War 1. Instead, the war at sea was one of blockades and sinkings and a small but feared U-boat. By August 1914 Germany and Britain were building massive and expensive warships - the dreadnoughts. The British controlled the North Sea, and built up supplies by commandeering all goods heading for Germany. Britain's survival depended on keeping her trade routes open, and for this reason Germany declared unrestricted submarine warfare on merchant shipping.