TheCodeBreakers
U-boats went on the air to report a toothache on board or to congratulate
a friend at headquarters on a birthday. U-boat command became "the
most gabby military organization in all the history of war."
Thanks to Commander Laurance F. Safford, head of OP-20-G and
father of the Navy's communications-intelligence organization, the United
States had, upon its entrance into the war, an Atlantic arc of high-
frequency direction-finders to exploit the U-boat garrulity. Stations
reported their bearings to their net control center in Maryland, whence
they were flashed to the naval communications-intelligence organization
at 3801 Nebraska Avenue, North West, in Washington. Commander
Knight McMahon and his staff combined them into fixes and flashed
these to the Atlantic Section of the Navy Commander in Chief's Combat
Intelligence Division. From here they sped to antisubmarine forces.
How fast this net—called "huffduff' from the HF/DF abbreviation of
annaabi.ee 
