Did you know at what distance the Chain Home radar could detect aircraft?

Chain Home had a range of 100 miles (160 km), a figure that its experimental system had already exceeded in early 1936. At that distance, the CH systems picked up enemy aircraft while they were forming up over France, which gave RAF commanders ample time to place their fighters on the raid's route. The effect has been described by saying it was as if they had three times as many fighters, which allowed them to frequently defeat larger German forces.

Chain Home was the world's first early-warning radar network and the first military radar system to become operational. When the war began, most of the country's east and south coasts already had radar coverage.

At ground level the gain was zero, so an aircraft could escape detection by flying at low altitude.