The war against U-boats in the Atlantic was won in part by a high-frequency direction finder - called Huff-Duff or HF/DF for short - that could pinpoint the location of radio transmitters. The electronic device was used extensively by the Allies to locate German submarines attacking merchant ships in the Atlantic. Yet it remained little known and understood, while its counterparts, sonar and radar, became household words. The story of HF/DF's development and operation in combat by the U.S.

Navy, told here for the first time in revealing detail, is a fascinating tale of determination and success.

Many countries, including Germany, had known about the technology of direction finding for some time, but none had been able to develop an adequate shipborne device. This left Admiral Donitz confident that his U-boats had little to fear. Simultaneously, a brilliant young French engineer working for ITT in the United States managed to create a device that was both dependable and practical. Eventually, the British produced a shipborne HF/DF that they used to good effect in the North Atlantic.

This book demonstrates how the vital American version was produced - and aggressively promoted by private enterprise to top American military officials. The author describes its acquisition by the U.S. Navy and the joint effort by the Navy and ITT to see that the device was properly installed and personnel adequately trained in its operation.