"Japan’s Panama Canal Buster II" Topic
14 Posts
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Tango01 | 01 Dec 2017 9:12 p.m. PST |
"In December 1944, the Imperial Japanese Navy organized the 1st Submarine Flotilla and 631st Kokutai (Air Corps), with Captain Tatsunoke Ariizumi commanding both units. The force consisted ofI-400, I-401 and two AM-class subs, I-13and I-14, which were smaller and carried two Seirans each, for a total of 10 Seiran bombers. An experienced naval officer from a distinguished military family, Ariizumi and had been in charge of the midget sub attacks at Pearl Harbor. In March 1945, Vice Adm. Jisaburo Ozawa, vice chief of the navy general staff, toyed with a plan to use the Seirans to unleash biological weapons on a U.S. West Coast city in revenge for the firebombing of Tokyo. The notorious Japanese Unit 731 had already conducted successful experiments in Manchuria using rats infected with bubonic plague and other diseases to kill Chinese citizens. But the operation was canceled later that month by General Yoshijiro Umezu, chief of the army general staff, who declared, "Germ warfare against the United States would escalate to war against all humanity." Instead, the Japanese decided to target the Panama Canal. By 1945 there was little doubt among the Japanese that the war was going badly. If Germany was defeated, the Allies would be on their doorstep next. The Panama Canal was a major transshipment point for war materiel essential to the Pacific theater. Closing it off would slow down if not stop the Allied advance, which would give Japan much-needed breathing room. As a result, the plan to attack the canal, drain Gatun Lake and block Allied shipping made strategic sense…" Main page link Amicalement Armand |
ScottWashburn | 11 Dec 2017 7:14 a.m. PST |
An interesting scheme. I think the Japanese would have been VERY lucky to manage to breach both ends of one of the locks at once which would have been necessary to drain Gatun Lake. |
Lion in the Stars | 18 Dec 2017 6:52 p.m. PST |
A brilliant idea that the Japanese should have pursued in December 1941 or early 1942. Today we'd have to use submarine-launched cruise missiles or maybe SUBROC nuclear depth charges. |
Charlie 12 | 20 Dec 2017 8:41 p.m. PST |
Not so brilliant. Given the level of defenses around the canal, the IJN wouldn't have a prayer in hades of getting within a hundred miles of the locks. Its also obvious that the author hasn't a clue about the canal's construction (draining Gatun Lake? Not at ALL likely) nor its defenses (yes, Virginia, the US did have an idea of just how valuable the canal was). Pure fantasy by clueless IJN officers reaching for straws. And this moronic author gives them full credence (and that's sadder still…). |
Mark 1 | 22 Dec 2017 5:06 p.m. PST |
Given the level of defenses around the canal, the IJN wouldn't have a prayer …. Its also obvious that the author hasn't a clue about the canal's construction … nor its defenses …. Pure fantasy by clueless IJN officers …. And this moronic author gives them full credence… So what WERE the defenses that would have prevented 3 submarines from approaching within 100 miles? I'm not saying they weren't there, but I don't know what they were and would be interested to hear. If you draw a circle at 100 miles' radius, you have a very substantial arc to defend -- even moresoe if you draw the circle at 200 or 300 miles (to give you some depth in which to make your detection and successful interception). So how many dozens of warships and how many squadrons of planes were patrolling those seas in 1944? I can recall reading about first-line fighter squadrons that went to Panama soon after Pearl Harbor. While P-35s were still defending the skies over the Philippines, precious P-39s and P-38s were being sent to defend Panamanian airspace. This was because the US was indeed very aware of the strategic importance of the Canal. But that was in early 1942. I can't recall seeing anything about 1944. -Mark (aka: Mk 1) |
thomalley | 22 Dec 2017 9:10 p.m. PST |
By the time the build-up was complete, defenses consisted of nine airbases and airdromes, 10 ground forces posts, 30 aircraft warning stations, and 634 searchlights, antiaircraft gun positions and miscellaneous tactical and logistical installations. Twelve outlying airbases were also constructed in Peru, Ecuador, Guatemala, Nicaragua, and Costa Rica. An outer defense parameter of 960 nautical miles from the Canal was established and patrolled by air and sea. Against 10 bombers |
Charlie 12 | 23 Dec 2017 10:18 p.m. PST |
Plus long range radar (placed in 1939), torpedo nets across all the locks (also added in 1939), and several squadrons (long range recon and fighter, also in 1939). By 1941, the canal was pretty heavily defended. By 1944 (thanks, thomalley), impregnable… |
Mark 1 | 26 Dec 2017 12:55 p.m. PST |
Great info! Thanks, guys. The Aichi Seiran bombers built for the I-400 and -401 seems to have been an interesting plane. Given the need to store multiple planes in a tubular hanger on a submarine deck, they were surprisingly current in performance, with nearly a 300mph speed and 1,800lb bomb load. Far more capable than the Yokosuka "Glen" float-plane launched from the I-25 a couple times to attack the Pacific Northwest with incendiary bombs in 1942, which may well have been a monoplane built in 1941, but still had performance reminiscent of WW1 aircraft (including fabric covered wings and an 85mph cruise speed). As I understand it the Seirans were painted with US markings prior to setting out on the Panama mission (the mission later re-directed to an attack on the USN Ulithi anchorage). But still, I doubt that several planes inbound from the ocean would not have stimulated an active intercept, and even with US markings any visual contact by interceptors would likely have caused only momentary hesitation. There were very few US float planes with dual float configurations (USN preferred a single main float with two outboards on the wings), and there could be no explanation for multiple unfamiliar aircraft types continuing to approach and not responding to interrogatories. With 900+ miles of depth to the defense there is every reason to expect that there would have been ample time to detect multiple planes, alert the defenses, intercept at least most of them, and overcome any hesitation. Given the level of defenses around the canal, the IJN wouldn't have a prayer in hades of getting within a hundred miles of the locks. I agree. Sounds like the defenses were indeed far beyond the scope of the contemplated attack. Still an interesting scheme for attack. I suppose the Japanese, by that late point in the war, had very little resource for assessing the active defenses in place around the Panama Canal. Or maybe they just were still stuck in their peculiar hubris of spiritual superiority. -Mark (aka: Mk 1) |
ScottWashburn | 03 Jan 2018 11:04 a.m. PST |
In Hector Bywater's classic alternate history story "The Great Pacific War" written in 1925 about a hypothetical US-Japanese war in 1931, he has the Japanese put the canal out of action at the start of hostilities by using an enormous bomb in a merchant ship going through the canal. Not an unreasonable ploy, actually. (It's actually a pretty good book, too.) |
138SquadronRAF | 03 Jan 2018 8:52 p.m. PST |
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Lion in the Stars | 17 Jan 2018 12:25 a.m. PST |
OK, the torpedo nets would have made a serious problem for the initial Japanese plans. But how vulnerable would the locks be to a 1500+lb armor-piercing bomb impacting on the dry side (say, a modified 15" shell)? That'd be another direction to attack, and well within the capabilities of the M6A Seiran. I'd expect that the Seirans would be launched without their floats, no point in recovering them after the strike. It'd take too long to get the airframe back onboard and stowed. Ditch the plane by the sub and recover the pilot only, then crash dive and run like hell. A Seiran without floats with US markings would confuse people. Too bad those took far too long to get flying, they needed to be ready in 1941. Nevertheless, the Japanese really needed to pull that plan off in 1941 or early 42, shortly after Pearl Harbor. This would force the LANTFLT reinforcements to come around the long way through the Straits of Magellan (crappiest water known to man, waves big enough to turn a battleship into a submarine), which would also allow the IJN to engage the surviving LANTFLT ships between New Zealand and Chile. I'd expect to lose several DDs and maybe some CLs going through the Straits of Magellan during the Southern Winter (June-July-August).
But that plan also requires catching the carriers at Pearl Harbor and destroying the submarine pens. Had the Mk14 torpedoes been up to spec, the Japanese merchant fleet would have been shredded by mid-1943 at the latest, since the USN declared unrestricted submarine warfare 6 hours after the Pearl Harbor attacks. Today, the USN unleashing the subs would see ~12 boats in the Pacific immediately (not counting SSBNs, though they could turn into scary-quiet attack boats if absolutely necessary), with another 12 or so surging as they could. Might see a few more boats loop around from the Atlantic, but that's about it (if the USN is unleashing the subs, SUBLANT is probably trying to beg boats from the Pacific to keep the Russians penned up and out of the convoy lanes). In 1942, unleashing the subs was more like 73 boats already in the Pacific, with another 38 submarines elsewhere and 73 more subs under construction (pretty much all of these subs went to the Pacific). The US built 228 more subs over the course of the war, and 'only' lost 52 of them (roughly 1 in 6, *shudder*). Between the carriers and the subs, the IJN got their butts kicked. |
ScottWashburn | 01 Feb 2018 12:33 p.m. PST |
Actually, the more I think about it, the less practical the idea becomes. Even if one of the locks was breached, we are talking about an enormous amount of water in Gatun lake (with more pouring all the time, the huge rainfall flowing into the lake is what made the whole Panama scheme work). It would take months for the lake to drain, and I'm sure some clever US engineer would have figured out a way to plug the hole in the lock with some sort of raft or hulk of some sort in a matter of days. Since the locks were in pairs, unless both locks were wrecked (unlikely) ships still could have made it through while the damaged lock was repaired. |
Charlie 12 | 01 Feb 2018 9:30 p.m. PST |
Drain Gatun Lake? ABSOLUTELY IMPOSSIBLE. You might want to take a look at the locks before putting up such an "interesting" idea. Each lock has multiple basins. The Gatun Locks have 3 basins, the Miraflores Locks 2 basins and Pedro Miguel Locks 1 basin. Each basin is separated by a set of gates (which are doubled). Each gate is made up of 2 sections which range from 500 to 800 tons each. And there are 2 locks (side by side) at each location. So to breach one of the Gatun Locks, you'd have to smash through 8 gates. And to smash the lock next to that one, another 8 gates. At the other end, that would also be 8 gates, plus 8 gates more. And to complicate things, each basin has an emergency damn in the middle that can seal the lock completely. That's 12 dams. So why don't try breaching the lock walls? Well, the side walls start out 50' wide and taper to 10'. And the center wall between the locks is 60' wide. And that's SOLID concrete. Your 1500lb bomb would bounce like a ping pong ball. For this job you'd need one of Barnes Wallis' 20K Earthquake bombs… Add in the multiple squadrons of fighters and patrol aircraft, several radars, many AAA sites, torpedo nets, etc. And that was in 1939! And you're going to do this with 10 planes….. YEAH RIGHT…. A Seiran without floats with US markings would confuse people For about 2 seconds…. |
Lion in the Stars | 11 Feb 2018 9:07 a.m. PST |
Don't need to completely destroy the locks, just need to make them unusable for 6+ months. Say, by triggering the use of that emergency dam you mentioned. |
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