I was under the impression that a Scotsman invented Radar and it was first implemented by the British in WW2.
The British were the first to use radar as a defense tool- implemented before WWII (mid to late 1930's), in order to detect Nazi aircraft. As ridiculous as it sounds, the British thought that the Nazi's were working on a Death Ray and asked the Air Ministry to investigate.
The Air Ministry, realized that a "Death Ray" was quite improbable, but that radar technology could be utilized in order to detect enemy aircraft, and the Chain Home network was then developed and installed.
Early Radar (as in WWII era Radar) was pretty unreliable, I remember reading in the book "Enola ***", about how many times the equipment on board the B-29's failed while they were carrying out practice runs and test runs.
