41:
59:
462:, the Army commander in Hawaii. However, Marshall was reluctant to use the telephone because he knew that telephone scramblers weren't very secure and sent it by less direct channels. Due to various constraints and bumblings, Short got the message many hours after the Japanese bombs had smashed the
371:
which went more on merit rather than rank (like
Bletchley Park), though commissions were handed out to "civilians in uniform" with rank according to age (an ensign for 28 or under, a lieutenant to 35 or a lieutenant commander if over 35). But control was by "regular military types". The Navy wanted
388:
had no relief officer (unlike the Army, with
Dusenbury and Bratton); and that night was being driven around by his wife. He was also responsible for distributing MAGIC information to the President; in January 1941 the Army agreed that they would supply the White House in January, March, May, July,
450:
machines. This sounded like war, and although the message said nothing about any specific military action, Kramer also realized that the sun would be rising over the expanses of the central and western
Pacific by that time. The two men both tried to get in touch with Army Chief of Staff General
389:
September and
November and the Navy in February, April, June, August, October and December. But in May 1941 MAGIC documents were found in the desk of Roosevelt's military aide Edwin "Pa" Watson and the Navy took over; while the Army provided MAGIC to the State Department instead.
280:
The classes were conducted by the Room 2426 crew, and the radiotelegraph operators became known as the "On-The-Roof Gang". By June 1940, OP-20-G included 147 officers, enlisted men, and civilians, linked into a network of radio listening posts as far-flung as the Army's.
383:
In 1940, SIS and OP-20-G came to agreement with guide lines for handling MAGIC; the Army was responsible on even-numbered days and the Navy on odd-numbered days. So, on the first minute after midnight on 6 December 1941 the Navy took over. But USN Lt-Comdr
549:
for $ 800,000 (a fraction of what the buildings and grounds were worth), in 1944, compensated $ 1.038 million. So on 7 February 1943 it opened at what was called the "Naval
Communications Annex", and staff moved in over the next two months.
502:(Communications Cryptanalytical section; to handle decryption and translation). Safford was shifted to an administrative support and cryptographic research role; thus was sidelined for the remainder of the war, as ultimately was
577:
July 10, 1946 All Naval communications intelligence elements were collectively designated "Communications
Supplementary Activities" of the 20th Division of the Office of Naval Communications, Section 2,
392:
The result was that much of the MAGIC was delayed or unused. There was no efficient process for assessing and organizing the intelligence, as was provided postwar by a single intelligence agency.
380:). A Royal Navy visitor and intercept specialist Commander Sandwith reported in 1942 on "the dislike of Jews prevalent in the US Navy (while) nearly all the leading Army cryptographers are Jews".
458:
After some agonizing delays, Marshall got the decrypts and methodically examined them. He realized their importance and sent a warning to field commanders, including Major
General
333:
was established in
Melbourne when Navy signals intelligence personnel from the Philippines were evacuated to Australia. Evacuated Army signals intelligence personnel went to the
210:
The Code and Signal
Section was formally made a part of the Division of Naval Communications (DNC), as Op-20-G, on July 1, 1922. In January 1924, a 34-year-old U.S. Navy
841:
831:
609:
277:
transmissions. Four of these men became instructors in the art of reading kana transmissions when the Navy began conducting classes in the subject in 1928.
836:
816:
599:
546:
179:
navies. In addition OP-20-G also copied diplomatic messages of many foreign governments. The majority of the section's effort was directed towards
416:
government to the
Japanese embassy in Washington, D.C. It was the last in a series of 14 messages that had been sent over the previous 18 hours.
348:(SIS) and OP-20-G were hobbled by bureaucracy and rivalry, competing with each other to provide their intelligence data, codenamed "
423:
analogue machine at OP-20-G and passed to the SIS for translation from Japanese, early on the morning of December 7. Army Colonel
248:
capacity in Japan and could speak Japanese fluently, but there was a shortage of radiotelegraph operators who could read Japanese
559:(July 1922-March 1935) Code and Signal Section (Op-20-G), Division of Naval Communications (DNC), OCNO (July 1922-March 1935).
284:
OP-20-G did some work on Japanese diplomatic codes, but the organization's primary focus was on Japanese military codes. The
219:
826:
510:
494:) for the centralizing of control of naval intercept and codebreaking in Washington. So two new sections were headed by
762:
736:
710:
532:
Another signals intelligence center, known as NEGAT was formed in Washington, using elements of OP-20-G headquarters.
361:
670:
A Priceless Advantage: U.S. Navy Communications Intelligence and the Battles of Coral Sea, Midway, and the Aleutians
218:
was assigned to expand OP-20-G's domain to radio interception. He worked out of Room 2646, on the top floor of the
188:
821:
545:
had picked out the "perfect new home" for the rapidly expanding OP-20-G and commandeered a private girls' school
357:
513:, a possible invasion of Hawaii, and greater demand for intelligence, OP-20-G undertook two courses of action:
409:
541:
In Summer 1942 the Navy went through the motions of perhaps co-locating with the Army's SIS but Commander
288:
first got a handle on Japanese naval codes in 1922, when Navy agents broke into the Japanese consulate in
604:
345:
263:
793:
353:
434:
The decrypts instructed the Japanese ambassador to Washington to inform the US Secretary of State,
779:
420:
296:
of pages of a Japanese navy codebook, and left, having put everything back as they had found it.
405:
241:
168:
199:, and continental U.S., as well as a Japanese telegraphic code school for radio operators in
751:
667:
349:
184:
156:
82:
8:
794:"The National Archives: Records of the National Security Agency/Central Security Service"
215:
487:
452:
367:
The Navy organization at OP-20-G was more conventionally hierarchical than the Army at
152:
64:
574:(October 1942-July 1946) Communications Intelligence Organization (Op-20-G), DNC, OCNO
758:
732:
725:
706:
699:
271:
237:
327:, with codebreakers and a network of listening and radio direction finding stations.
594:
517:
The staff and services of CAST were progressively transferred to a newly formed US-
503:
479:
424:
377:
223:
200:
120:
115:
97:
568:(October 1939-February 1942) Communications Security Section (Op-20-G), DNC, OCNO
413:
672:. Fort Meade MD: Center for Cryptologic History, National Security Agency, 1993.
588:
495:
478:
In February 1942 power struggles within the Navy resulted in the sidelining of
368:
334:
196:
167:. Its mission was to intercept, decrypt, and analyze naval communications from
125:
810:
720:
542:
499:
491:
439:
289:
233:
192:
160:
86:
46:
571:(February 1942-October 1942) Radio Intelligence Section (Op-20-G), DNC, OCNO
746:
565:(March 1939-September 1939) Radio Intelligence Section (Op-20-G), DNC, OCNO
467:
459:
435:
428:
385:
316:
310:
306:
176:
172:
164:
562:(March 1935-March 1939) Communications Security Group (Op-20-G), DNC, OCNO
483:
324:
299:
Before the war, the Navy cipher bureau operated out of three main bases:
293:
780:"The Pacific War: The U.S. Navy, Naval Intelligence as of Pearl Harbor"
320:
249:
211:
526:
518:
401:
376:
cipher machine like the Navy; though it was developed by a civilian (
245:
701:
Battle of Wits: The Complete Story of Codebreaking in World War II
753:"And I Was There": Pearl Harbor and Midway – Breaking the Secrets
463:
342:
285:
267:
259:
236:, but there was the problem of finding personnel who could speak
522:
447:
373:
330:
681:
679:
634:
443:
229:
180:
676:
622:
438:, at 1:00 PM Washington time that negotiations between the
274:
254:
400:
In the early hours of the morning of 7 December 1941, the
646:
270:
had formed an informal group in 1923 to compare notes on
352:", to high officials. Complicating matters was that the
319:, a section in the fortified caves of the island of
147:th Division of the Office of Naval Communications,
750:
724:
698:
446:were ended. The embassy was then to destroy their
615:
498:(Communications Combat Intelligence section) and
303:Station NEGAT at headquarters in Washington, D.C.
808:
600:United States Naval Computing Machine Laboratory
591:, one of the OP-20-G members during World War II
412:, picked up a radio message being sent by the
842:Signals intelligence agencies of World War II
663:
661:
536:
832:Military communications of the United States
151:Section / Communications Security", was the
837:Defunct United States intelligence agencies
658:
372:the Army to forbid civilians to touch the
266:radiotelegraph operators operating in the
187:. This was made possible by intercept and
696:
685:
628:
395:
183:and included breaking the early Japanese
139:or "Office of Chief Of Naval Operations (
817:Office of the Chief of Naval Operations
719:
640:
228:Japan was of course a prime target for
16:WWII US Navy signals intelligence group
809:
745:
652:
431:independently inspected the decrypts.
473:
364:also had radio-intercept operations.
553:
511:Japanese advances in the Philippines
404:communications intercept station at
13:
610:United States Coast Guard Unit 387
14:
853:
772:
419:The messages were decrypted by a
57:
39:
482:, with the support of Admirals
189:High Frequency Direction Finder
731:. New York: Crown Publishers.
616:References and further reading
547:Mount Vernon College for Women
427:and Navy Lieutenant Commander
1:
727:Pearl Harbor: Final Judgement
410:Bainbridge Island, Washington
757:. New York: William Morrow.
30:July 1, 1922 - July 10, 1946
7:
697:Budiansky, Stephen (2000).
582:
346:Signal Intelligence Service
258:. Fortunately, a number of
240:. The Navy had a number of
10:
858:
827:Cryptography organizations
537:Naval Communications Annex
309:(or FRUPAC), a section at
96:Navy Department building,
292:, cracked the safe, took
205:
108:
103:
92:
78:
70:
52:
34:
26:
21:
705:. New York: Free Press.
643:, pp. 45, 307, 308.
252:communications sent in
74:Code and Signal Section
822:Attack on Pearl Harbor
466:'s fleet at anchor in
396:Attack on Pearl Harbor
185:"Blue" book fleet code
668:Parker, Frederick D.
655:, pp. 367, 368.
244:who had served in a
191:(HFDF) sites in the
157:signals intelligence
83:Signals intelligence
688:, pp. 223–226.
631:, pp. 228–229.
216:Laurance F. Safford
521:-British station,
488:Richmond K. Turner
474:After Pearl Harbor
453:George C. Marshall
65:United States Navy
721:Clausen, Henry C.
554:Section evolution
232:interception and
131:
130:
849:
803:
801:
800:
789:
787:
786:
768:
756:
742:
730:
716:
704:
689:
683:
674:
665:
656:
650:
644:
638:
632:
626:
595:Fleet Radio Unit
504:Joseph Rochefort
480:Laurance Safford
425:Rufus S. Bratton
378:William Friedman
224:Washington, D.C.
201:Washington, D.C.
121:Joseph Rochefort
116:Laurance Safford
98:Washington, D.C.
63:
61:
60:
45:
43:
42:
19:
18:
857:
856:
852:
851:
850:
848:
847:
846:
807:
806:
798:
796:
792:
784:
782:
778:
775:
765:
739:
713:
693:
692:
684:
677:
666:
659:
651:
647:
639:
635:
627:
623:
618:
585:
556:
539:
476:
398:
360:, and even the
220:Navy Department
208:
134:
123:
118:
110:
85:
58:
56:
40:
38:
17:
12:
11:
5:
855:
845:
844:
839:
834:
829:
824:
819:
805:
804:
790:
774:
773:External links
771:
770:
769:
763:
743:
737:
717:
711:
691:
690:
686:Budiansky 2000
675:
657:
645:
633:
629:Budiansky 2000
620:
619:
617:
614:
613:
612:
607:
602:
597:
592:
589:Andrew Gleason
584:
581:
580:
579:
575:
572:
569:
566:
563:
560:
555:
552:
538:
535:
534:
533:
530:
496:John R. Redman
475:
472:
397:
394:
369:Arlington Hall
339:
338:
335:Central Bureau
328:
314:
304:
207:
204:
132:
129:
128:
126:John R. Redman
112:
106:
105:
101:
100:
94:
90:
89:
80:
76:
75:
72:
68:
67:
54:
50:
49:
36:
32:
31:
28:
24:
23:
15:
9:
6:
4:
3:
2:
854:
843:
840:
838:
835:
833:
830:
828:
825:
823:
820:
818:
815:
814:
812:
795:
791:
781:
777:
776:
766:
764:0-688-04883-8
760:
755:
754:
748:
747:Layton, Edwin
744:
740:
738:0-517-58644-4
734:
729:
728:
722:
718:
714:
712:0-684-85932-7
708:
703:
702:
695:
694:
687:
682:
680:
673:
671:
664:
662:
654:
649:
642:
637:
630:
625:
621:
611:
608:
606:
603:
601:
598:
596:
593:
590:
587:
586:
576:
573:
570:
567:
564:
561:
558:
557:
551:
548:
544:
543:Joseph Wenger
531:
528:
524:
520:
516:
515:
514:
512:
507:
505:
501:
500:Joseph Wenger
497:
493:
492:Joseph Redman
489:
485:
481:
471:
469:
465:
461:
456:
454:
449:
445:
441:
440:United States
437:
432:
430:
426:
422:
417:
415:
411:
407:
403:
393:
390:
387:
381:
379:
375:
370:
365:
363:
359:
355:
351:
347:
344:
336:
332:
329:
326:
322:
318:
315:
312:
308:
305:
302:
301:
300:
297:
295:
291:
290:New York City
287:
282:
278:
276:
273:
269:
265:
261:
257:
256:
251:
247:
243:
239:
235:
234:cryptanalysis
231:
226:
225:
221:
217:
213:
203:
202:
198:
194:
190:
186:
182:
178:
174:
170:
166:
163:group during
162:
161:cryptanalysis
158:
154:
150:
146:
142:
138:
133:Military unit
127:
122:
117:
113:
107:
102:
99:
95:
91:
88:
87:Cryptanalysis
84:
81:
77:
73:
69:
66:
55:
51:
48:
47:United States
37:
33:
29:
25:
20:
797:. Retrieved
783:. Retrieved
752:
726:
700:
669:
648:
641:Clausen 1992
636:
624:
540:
529:, Australia.
508:
477:
468:Pearl Harbor
460:Walter Short
457:
436:Cordell Hull
433:
429:Alwin Kramer
418:
399:
391:
386:Alwin Kramer
382:
366:
340:
317:Station CAST
311:Pearl Harbor
307:Station HYPO
298:
283:
279:
253:
227:
222:building in
209:
165:World War II
148:
144:
140:
136:
135:
653:Layton 1985
605:US Army SIS
506:in Hawaii.
484:Ernest King
354:Coast Guard
325:Philippines
294:photographs
93:Garrison/HQ
811:Categories
799:2006-12-07
785:2006-12-07
519:Australian
321:Corregidor
250:Wabun code
246:diplomatic
212:lieutenant
111:commanders
104:Commanders
35:Allegiance
578:(Op-20-2)
527:Melbourne
406:Fort Ward
402:U.S. Navy
323:, in the
313:in Hawaii
153:U.S. Navy
749:(1985).
723:(1992).
583:See also
414:Japanese
272:Japanese
242:officers
238:Japanese
197:Atlantic
169:Japanese
124:Captain
119:Captain
114:Captain
464:US Navy
343:US Army
286:US Navy
268:Pacific
260:US Navy
193:Pacific
177:Italian
137:OP-20-G
109:Notable
22:OP-20-G
761:
735:
709:
523:FRUMEL
448:cipher
421:PURPLE
374:SIGABA
356:, the
331:FRUMEL
264:Marine
214:named
206:Prewar
175:, and
173:German
143:NAV),
62:
53:Branch
44:
27:Active
509:With
490:(and
444:Japan
350:MAGIC
230:radio
181:Japan
759:ISBN
733:ISBN
707:ISBN
486:and
442:and
341:The
275:kana
262:and
255:kana
159:and
79:Role
71:Type
525:in
408:on
362:FCC
358:FBI
155:'s
813::
678:^
660:^
470:.
455:.
195:,
171:,
145:20
141:OP
802:.
788:.
767:.
741:.
715:.
337:.
149:G
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.