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Radar: Britain's secret weapon

German pilots attacking from France often flew straight into a swarm of British fighters, who seemingly were waiting for the attack and deprived the enemy of the element of surprise. It was the power of radar, combined with intelligence gathered from radio chatter and the Observer Corps that gave Fighter Command the edge.

Chain home radar station

Ironically, it was two German scientists who led the way in the development of radar. Heinrich Hertz in 1886 demonstrated that radio waves reflected from solid object and Christian Hülsmeyer in 1904 actually patented a system for detecting ships.

And while many countries' militaries were secretly pursuing radar in the 1930s, Great Britain was the only country to have an operational system in place at the outbreak of the war.

The intelligence from this system alerted Fighter Command to incoming aircraft, allowing fighters to scramble and meet the enemy with just seconds to spare.

Physicist Robert Watson-Watt led a team in the UK that eventually developed the Chain Home system, with the support of Air Chief Marshal Dowding. In place in 1939, the system consisted of 52 High and Low level stations around the Southeast coast.

The high level stations detected aircraft at an altitude of up to 20,000 feet and a distance of 200 miles, while the low level radar detected aircraft at a shorter range and an altitude of up to 500 feet.

Incoming waves of German aircraft were detected over the Channel and this intelligence was transmitted to the command centre at Bentley Priory. 

The Observer Corps (designated the Royal Observer Corps in 1941) corroborated the data and relayed the number, type, and altitude of incoming aircraft after they reached the British coast.

Additional intelligence was gleaned by WAAFs and WRENs stationed at RAF West Kingsdown, who monitored German airmen's radio conversations for targeting information.

These sources of intelligence gave Britain an important edge and thwarted the Germans to the point that on 12 August they changed tactics and began attacking the Chain Home stations.

The above ground control rooms at many of the stations were damaged with significant loss of life, but many of the towers survived and were quickly brought back on line. On 15 August, the attacks on the radar stations were called off as the Germans thought their attacks ineffective, leaving one of the UK's key assets intact.

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