At the outbreak of World War 2 German radar technology was superior to that of the British. However, the British had launched a project to surround most of the coastline of Britain with an extensive chain of radar stations that were not individually sophisticated but which could function effectively when working in coordination with each other. This project, known as Chain Home, produced the world's first integrated air defence system.
Chain Home proved invaluable in the Battle of Britain during the summer and autumn of 1940, allowing the outnumbered RAF to effectively target German aircraft, denying the Luftwaffe air superiority and thwarting Hitler's plans for an invasion.
In 1944 some of the Chain Home stations were re-purposed to report on German V2 rocket launches as part of a project known as Big Ben.