The Tenth Fleet and F-21
Steadily developing an intelligence advantage, Admiral Ernest J. King, U.S. Navy Chief of Naval Operations and Commander in Chief (COMINCH), met with British and Canadian naval leaders in Washington for the Atlantic Convoy Conference in March 1943. In the conference, King introduced a new Allied strategy, proposing a realignment of authority whereby the British, Canadians, and Americans controlled their own forces in the Atlantic. After some deliberation, the idea was endorsed by the British and Canadian delegations. According to the arrangement, Britain and Canada shared the responsibility of controlling the North Atlantic seaways, while the U.S. Navy assumed control over the central and southern Atlantic. Shortly after the March conference, King created Tenth Fleet. Vessels were not specifically assigned to Tenth Fleet, and the organization essentially served as an antisubmarine command.
At the heart of Tenth Fleet operations, Knowles and his F-21 submarine tracking room staff collected and disseminated the most current operational intelligence on Axis naval operations. Most of the information processed in F-21 was based upon HF/DF and RADAR fixes, rather than just cryptologic sources. Contrary to many post-ULTRA declassification reassessments, Knowles observed in one report that cryptologic intelligence was mostly unavailable on a timely basis for extended periods. He further remarked that "[e]ven when the enemy's cipher is broken, there are many times when the navigational positions are still unreadable." Photographs of the Knowles tracking room illustrate how all the various forms of U-boat tracking information were recorded on the main wall charts in F-21. To limit access to raw cryptologic intelligence, Knowles created the F-211 "Secret Room" as a separate section within F-21. Once cryptologic intelligence was sufficiently sanitized in the confines of the Secret Room, the data was transferred to the main charts in the adjacent F-21 plotting room, where the intelligence could be analyzed and exploited at an operational level. Once F-21 personnel evaluated and organized the intelligence, the information was customarily transmitted to the Admiralty and, to a lesser extent, the Canadian tracking room in Ottawa. Together, Winn and Knowles worked hard at maintaining current and uniform plots on U-boat locations and dispositions. Meanwhile, the relationship between Winn at the Admiralty and Knowles in F-21 evolved in conjunction with the changes in the Allied war effort in the Atlantic. Under Winn, the Admiralty tracking room continued performing the primary tactical functions of maneuvering convoys away from danger, while Knowles and his F-21 staff provided accurate intelligence to U.S. Navy forces through Tenth Fleet. Eventually, the Americans reshuffled tactical assets, using special intelligence to attack U-boats. << Previous | Page 2 of 3 | Next >>
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