p. 46
Admiral J.O. Richardson, the fleet commander at Pearl Harbor, indicated that the depth of water at Taranto was approximately 90 feet,
or marginal for dropping torpedoes. Since the depth at Pearl Harbor was only 45 feet, torpedo attacks were impossible27.
Yamamoto, however, found that the depth at Taranto was 42 feet or less, and that the British torpedoes had been modified to ensure
proper running in shallow water, even in the shallow waters of Pearl Harbor28.
Nevertheless, if one could wade through the numerous reports, newspaper articles and opinions, historic events, and varying
naval views and prejudices, separating the relevant from the extraneous, all the signs pointing to an attack on Pearl Harbor
were there. Historically, when Japan's relations with other countries grew tense, the Japanese habitually started war with
very well-planned attacks and actually declared war after the fact...
27Dyer, On the Treadmill to Pear Harbor, p. 363.
28Potter, Admiral of the Pacific, p. 53; Thomas P. Lowry and John W.G. Wellhan,
The Attack on Taranto: Blueprint for Pearl Harbor (Mechanicsburg, PA: Stackpole Books, 2000),
p. 39. Though Potter reports the Mk 12 torpedoes had wooden fins added to permit use in shallow waters, the latter describes
a fine wire coiled on a drum, which connected the torpedo to the plane. Breaking point of the wire insured proper depth
and angle for running in shallow water. The sunken ships rested on the bottom of the harbor with their superstructures
remaining above water. Torpedoes were launched from an altitude of 50 feet or less.
Mr. Canfield developed weapon fire control equipment for the U.S. Navy over 38 years with General Electric and was director
for the Center of Research and professor at the Watson School of Engineering at Binghamton University, New York.
pp. 361-63
Torpedo Baffles in Pearl
This discussion, up to now, has been about air reconnaissance.
There is another aspect of the security of the Fleet at Pearl Harbor, on which my staff and I faulted pretty completely, and I do not wish, by omitting mention of the matter, to dodge the issue or avoid my share of the responsibility, if there were such.
The British had made a very successful night-aircraft torpedo attack on the heavy ships of the Italian Fleet at anchor in the harbor of Taranto, on November 11-12, 1940. When the extent of this success became known, several members of my staff gathered together the meager data available on the individual attacks, including height of planes and depth of water at launching point, length of torpedo runs before reaching target, and angles of torpedo entry into water, and the matter was considered in relation to the security from torpedo attack of our own Fleet at anchorages at Lahaina and Pearl. It was quite obvious that the Lahaina anchorage was very vulnerable from every consideration. This was the major factor which caused me to reduce to practically zero the time the Fleet spent at anchor at Lahaina, after the middle of November 1940. It seemed to me to be best that the Fleet should either be underway at sea, or berthed inside Pearl Harbor.
In Pearl Harbor, it was a fact that torpedoes, with the characteristics of the then available or projected United States air-carried torpedoes, could not be used effectively against berthed ships. Our then operating air torpedoes dove very deep when launched, and took some hundreds of yards before rising to their desired running depth. They did not arm until about back at running depth51.
In the Fleet staff there was no knowledge or intelligence of Japanese aircraft torpedoes which were operable under the limiting condition in Pearl Harbor of only 35-45 feet of water at possible launching points. Hindsight indicates that a sounder decision would have been to press home an independent investigation as to whether such torpedoes were a possibility, and not to dismiss the matter on the grounds that we had no intelligence of Japanese or other foreign torpedoes of such a capability. It was erroneous to assume that since a torpedo attack on berthed ships at Pearl was beyond our own torpedo capabilities, it was also beyond the capabilities of the Japanese. Such an investigation might have revealed that the British had made an air torpedo attack on the French battleship Richelieu at Dakar, in July 1940, and “The charted depth at the dropping position was only 7 fathoms.” As a result of our review of the matter, on November 28, 1940, I dismissed the air torpedo threat with these words in a letter to CNO. “I think torpedo nets within the harbor [Pearl] are neither necessary nor practicable. The area is too restricted and ships, at present, are not moored within torpedo range of the entrances.”52.
Shortly after this (February 15, 1941), the Chief of Naval Operations, in a lengthy letter53, presented to my successor some basic data available to the Department in regard to torpedo capabilities and anti-torpedo baffles, and requested his recommendation in regard to the installation of anti-torpedo baffles in Pearl Harbor. The information presented was no different from that which had been available to me, and my successor's recommendation, unfortunately, was much the same as mine.
There is another aspect of the security of the Fleet at Pearl Harbor, on which my staff and I faulted pretty completely, and I do not wish, by omitting mention of the matter, to dodge the issue or avoid my share of the responsibility, if there were such.
The British had made a very successful night-aircraft torpedo attack on the heavy ships of the Italian Fleet at anchor in the harbor of Taranto, on November 11-12, 1940. When the extent of this success became known, several members of my staff gathered together the meager data available on the individual attacks, including height of planes and depth of water at launching point, length of torpedo runs before reaching target, and angles of torpedo entry into water, and the matter was considered in relation to the security from torpedo attack of our own Fleet at anchorages at Lahaina and Pearl. It was quite obvious that the Lahaina anchorage was very vulnerable from every consideration. This was the major factor which caused me to reduce to practically zero the time the Fleet spent at anchor at Lahaina, after the middle of November 1940. It seemed to me to be best that the Fleet should either be underway at sea, or berthed inside Pearl Harbor.
In Pearl Harbor, it was a fact that torpedoes, with the characteristics of the then available or projected United States air-carried torpedoes, could not be used effectively against berthed ships. Our then operating air torpedoes dove very deep when launched, and took some hundreds of yards before rising to their desired running depth. They did not arm until about back at running depth51.
In the Fleet staff there was no knowledge or intelligence of Japanese aircraft torpedoes which were operable under the limiting condition in Pearl Harbor of only 35-45 feet of water at possible launching points. Hindsight indicates that a sounder decision would have been to press home an independent investigation as to whether such torpedoes were a possibility, and not to dismiss the matter on the grounds that we had no intelligence of Japanese or other foreign torpedoes of such a capability. It was erroneous to assume that since a torpedo attack on berthed ships at Pearl was beyond our own torpedo capabilities, it was also beyond the capabilities of the Japanese. Such an investigation might have revealed that the British had made an air torpedo attack on the French battleship Richelieu at Dakar, in July 1940, and “The charted depth at the dropping position was only 7 fathoms.” As a result of our review of the matter, on November 28, 1940, I dismissed the air torpedo threat with these words in a letter to CNO. “I think torpedo nets within the harbor [Pearl] are neither necessary nor practicable. The area is too restricted and ships, at present, are not moored within torpedo range of the entrances.”52.
Shortly after this (February 15, 1941), the Chief of Naval Operations, in a lengthy letter53, presented to my successor some basic data available to the Department in regard to torpedo capabilities and anti-torpedo baffles, and requested his recommendation in regard to the installation of anti-torpedo baffles in Pearl Harbor. The information presented was no different from that which had been available to me, and my successor's recommendation, unfortunately, was much the same as mine.
51“A minimum depth of water of seventy-five feet may be assumed
necessary to successfully drop torpedoes from
planes. One hundred and fifty feet of water is desired.
The maximum height planes at present experimentally drop torpedoes is 250
feet... Desirable height for dropping is sixty feet or less. About two hundred yards of torpedo run is necessary before the
exploding device is armed, but this may be altered.” For the successful attacks at Taranto “...the depths of water
in which the torpedoes were launched were between 14 and 15 fathoms.” CNO serial 09330 of 15 Feb. 1941, letter to
CINCPACFLT, as cited in Pearl Harbor Hearings, Part 26, pp. 523-24. “The depth of water in and alongside available
berths in Pearl Harbor does not exceed 45 feet.” This is in reply to CNO, serial 010230 of 17 Feb. 1941, letter to COM14.
52Pearl Harbor Hearings, Part 14, p. 975; Ibid.,
Part 26, pp. 523-24; Ibid., “Narrative Statement of Evidence”, p. 231.
53Ibid., Part 26, pp. 523-25.
It does look like they were given very “meagre data” indeed or a heavily censored [read: doctored] US or British Taranto report, while the real things, with attached sketches, were sitting on the CNO's and several other desks, or drawers, in Washington - besides with the President who received at least one, at once, directly from Winston Churchill, and must have discussed it with the Navy he felt so close to.
So much for Pearl Harbor Hearings. Taranto taught Yamamoto that Pearl Harbor could, after all, be done, but otherwise he ‘found’ nothing. He just had proper, easy intelligence - there was an Axis Pact - and harbor depths have nothing to do with covert intelligence, being only a matter of good Merchant Marine cartography publicly available; not to mention Naval attachés of all sides around the globe, like John Opie extensively covered in this site. [When, by the way, is Lieutenant Commander [later RAdm.] John Newton Opie, III, USN - discovered by us years ago in a vague message on the web and dug out of the National Archive by Michael Yudell - finally going to be acknowledged?]
The US Navy cannot make itself pass forever as an accidental tourist in 1940-41. There is no mention in the article of Lt. Cmdr. Opie or of his report, nor of the August 1940 tale-telling Raid on Bomba Bay (maps here), Libya - of which Opie knew - by the same pilots of Taranto, and Billy Mitchell is there but Admirals Stark, Ingersoll and Kimmel are not.
The Opie and the British reports certainly could not, even now, have been confused among “the numerous reports” mentioned by Canfield, which are so dear a pretext to most authors. This coiled-wires ‘première’ [publicly mentioned by an author in a magazine for the very first time in 65 years, except for Lt. Cmdr. Wellham's own books, A.J. Smithers and ourselves] is not duly underlined in a special note to the article and seems quietly slipped in, giving the impression that it should go unnoticed in tiny print instead of jolting anyone. And never mind that the tethered Mk XII was shallow-water standard equipment. In With Naval Wings, John Wellham tells: “our torpedo men lavished care on them and we had never suffered a failure in the past.” The relative novelty on the torpedoes was a “Duplex contact/magnetic pistol” mentioned with pride by Churchill in his attached note to FDR. As we said elsewhere, no one was foolish enough to gamble a pivotal mission like Taranto by saddling torpedoes with coiled wires that were not well-proven. Not only. VAdm. B.B. Schofield, RN, wrote:
“They were fitted with Duplex pistols which the Illustrious had brought from England and which had only come into service shortly before the outbreak of the war. They differed from the ordinary contact pistols in that they included a device actuated by an enemy ship's magnetic field as the torpedo passed underneath her and which fired the primer and exploded the warhead.”And A.J. Smithers:
“The only ones available to the Fleet in late 1940 were, in any event, a little behind the times. The 18-inch Mk XIIs* were to be set to run at 27 knots with a depth of 33 feet - sufficient to circumvent any net - and with 100 yards run off the safety range. All would be set to remain alive at the end of their run and each contained roll of cable which unwound and held the angle after dropping as well as inhibiting ‘porpoising’ or diving too deeply. Only contact with the water was needed in order to set the propellers turning and to speed the missile on its way. The Japanese 24 inch, oxygen-powered Long Lance was a more powerful weapon in every way but its time had not yet come.”What more is needed, and... how would Dr. Roberta Wohlstetter have taken all this? Washington's knowledge of the wires, at the very least since Nov. 1940, is, instead, a capital element of the Pearl Harbor mural. Without an even larger fresco of the origins of WW II, the other very important seeds leading to Pearl Harbor and the side-effect role of the attack itself cannot be summarized. The origins of WW II and their partly unresolved ripples to this day are the reason for Sorge, A Chronology, nearing completion. The coiled torpedo-wires, studiously avoided by everyone until Canfield's article, say one important thing when you connect them to Adms. Stark and Ingersoll's ambiguous [see Wohlstetter and p.3 of US Fleet Aircraft Tactical Unit of Air Operations Summary about Taranto attack] letters to Adm. Kimmel too many months after Taranto: Stark, Ingersoll, and for that matter Capt. Richmond Kelly Turner and his pre-Pearl Harbor U-turn, were not incompetent, fools, remiss or traitors. The only alternative left to explain their treatment of the Taranto reports and of those Mk XIIs is that, along with others, they had to be under orders [like Joseph Grew, the US ambassador to Japan with whom the whole imbroglio maybe started long before, on 26 and not 27, Jan. 1941? See: Mrs. Rivera-Schreiber's affidavit, interview and the comments]. We have shown plenty but not yet all we have on this subject on our web-site. Anyhow - under whose orders these men most probably were is now for the readers to demand or find out, and why not also for the Naval History magazine? Giovanni Volpi*Lieutenant-Commander Wellham, whose acquaintance any possible reader will soon be making, has been kind enough to tell me that the reference in the Official Report to a Mk XIII is probably a misprint. There never was a Mk XIII. [Those came later]
30 December, 2004 Additional information is welcome at: For a quick glance at Admiral Richardson's book, On the Treadmill to Pearl Harbor: The review written by Martin Merson, January 1988 - click here (pdf). Reopen the Kimmel Case, by Michael Gannon. Naval Institute of Proceedings, December 1994. - click here (pdf). Resurrecting the Kimmel Case, by Fred L. Schultz, EiC of the Naval History magazine, February 2004. - click here (pdf).
