This led to the formation of the first integrated ground-controlled interception network, the Dowding system, which collected and filtered this information into a single view of the airspace.[lower-alpha 1] Dozens of CH stations covering the majority of the eastern and southern coasts of the UK, along with a complete ground network with thousands of miles of private telephone lines, were ready by the time the war began in 1939. Chain Home proved decisive during the Battle of Britain in 1940; CH systems could detect enemy aircraft while they were still forming up over France, giving RAF commanders ample time to marshal their entire force directly in the path of the raid. This had the effect of multiplying the effectiveness of the RAF to the point that it was as if they had three times as many fighters, allowing them to defeat the larger German force.