15:19 (Hawaii Time)
Sunday, July 12, 1942
Control room of the U-800
On silent cruising off Pearl Harbor, Oahu
Hawaii
Lieutenant-commander Takeshi Nagaoka quietly and unobtrusively went around the control room of the U-800, watching the crewmen on duty do their work. A quick look at the depth gauge demonstrated again to Takeshi that the U-800 was no ordinary submarine: it was actually cruising at three knots at a depth of 230 meters, deeper than any Japanese or American submarine could dive and deep enough to basically render it invulnerable to American depth charges, which could not be set to explode past 200 meters. Yet, the U-800 was doing a lot more than just sailing around quietly: it was also listening for potential preys with its towed passive hydrophone array, which was presently trailing 200 meters behind and ninety meters above the U-800, traveling above the local water thermal layer. While the U-800’s towed array could easily listen for ships and submarines located above the thermal layer, any ship using its sonar set would see its acoustic signal reflected or deformed as it hit the thermal layer, making the U-800 nearly undetectable at its present depth. Otto Kretschmer had fully used that advantage on his trip to Hawaii, on top of demonstrating another superior feature of his U-800 by routinely spending over twenty hours per day deeply submerged while speeding along at twelve knots, then going up briefly for a few hours at the most in the dead of the night, letting only his schnorchel mast and electronic warfare mast emerge while he recharged his batteries via his three big diesel engines. Even when recharging with his noisy diesels, Kretschmer was able to keep a careful acoustic vigil thanks to his towed hydrophone array, trailing far behind and away from the machinery noise of the U-800. As a result of all this, not one American warship or patrol aircraft had been able to detect the U-800 during its approach to Hawaii, while the German submarine had more than one occasion when it could have easily taken an American warship by surprise and sunk it. Kretschmer had however wisely decided, in Takeshi’s opinion, to ignore those potential preys, in order to preserve the moment of surprise until a truly worthy prize showed up in his sights. By ‘worthy prize’, he meant an aircraft carrier or, at the least, a battleship or a heavy cruiser. On his part, Takeshi fervently wished that Otto would encounter an American aircraft carrier. After the disastrous battle of Midway, where the Imperial Japanese Navy had lost no less than four of its fleet carriers against only one American carrier sunk, the sinking of even one American aircraft carrier by the U-800 would do a lot to give back some advantage to Japan in the Pacific. Having been exposed now for weeks to Otto Kretschmer’s tactical and strategic way of thinking and observing the successes brought by that thinking, Takeshi now understood that the Imperial Japanese Navy’s submarine arm was making a grave mistake by not making attacks on the American and British merchant fleet. Worse, the Japanese Navy was underestimating in turn the danger that American submarines represented to its own maritime lines of communications. The Japanese Navy could indeed learn a lot about submarine warfare from its ally, the Kriegsmarine.
The rest of the day and the night went quietly aboard the U-800, with only cargo ships, fishing vessels and warships no bigger than destroyers detected going in and out of Pearl Harbor and of the port of Honolulu. The American destroyers that went around however proved quite active, using their sonar sets nearly constantly, while patrol boats and even a couple of submarines crisscrossed Mamala Bay, into which the entrance channel of Pearl Harbor opened. It was quickly clear that the U.S. Navy was on the alert for the U-800 and exercised maximum caution around Hawaii. Otto was in turn cautious, not wanting to underestimate an alert enemy, and went up to periscope depth at night only to confirm his position and to recharge his batteries with his diesel engines. The next two days proved equally uneventful, something many in the crew, including Kretschmer, thankfully used to catch up on their sleep.
05:52 (Hawaii Time)
Wednesday, July 15, 1942
Sonar section, U-800
Mamala Bay, Oahu
Hans Bock, on duty at the time with Gerhard Hoepner in the sonar section, stiffened in his chair and closed his eyes for a moment as he concentrated to mentally analyze the noises his hydrophones were now picking up. He then played with his controls to refine the direction and frequencies of those noises before calling the watch officer, Hermann Spielberger, via intercom.
‘’Leutnant, this is Bock, at the hydrophones. I am picking up the machinery and propeller noises of multiple ships preparing to leave Pearl Harbor. Some of those ships are heavy units.’’
‘’I’m coming!’’ Replied at once Spielberger from the control room. It took him less than ten second to come to the sonar section, situated aft of the control room.
‘’How many ships can you count, Bock?’’
‘’At least a dozen, Herr Leutnant, including three big ones.’’
‘’That sounds like a task force about to go to sea. The Kapitän will want to hear about this.’’
Spielberger then went out of the sonar section and went down one deck, to go knock on the door of Kretschmer’s cabin.
‘’Herr Kapitän! Herr Kapitän! Wake up! We have a possible enemy flotilla about to leave Pearl Harbor.’’
Less than ten seconds later, Otto Kretschmer opened his door, his eyes still sleepy, to face Spielberger.
‘’What do we have exactly, Spielberger?’’
‘’Our hydrophones are picking up over a dozen ships about to leave Pearl Harbor, including three big ones, Herr Kapitän.’’
‘’Very well! Call the crew to battle stations…quietly. Reel in our towed array and head towards the entrance channel of Pearl Harbor at ten knots. I want us to be in ambush position before those ships can leave Pearl Harbor and form up properly.’’
‘’Understood, Herr Kapitän!’’ Replied the junior officer before leaving at a run to go back to the control room. As for Otto, he closed his door and went to his closet to quickly dress. Shaving would have to wait. Two minutes later he was climbing the ladder leading to the control room, where he went immediately to the tactical plot table, beside which Spielberger stood.
‘’How far are we from the minefields protecting the entrance channel of Pearl Harbor? Have any of those ships left port yet?’’
Spielberger put an index on a point of the chart laid out under a plastic transparent film on the tactical plot table.
‘’We are presently here, about eleven nautical miles from the outer limits of those minefields, Herr Kapitän. The first of the enemy warships is now about to slip down the entrance channel towards the open sea.’’
‘’Good! Raise our speed to fifteen knots for ten minutes, then slow down to two knots and place us into an ambush position here, one nautical mile to the west of the opening of the entrance channel. With some luck, we will be in position before any destroyer screen could form up once out of the channel.’’
‘’Yes, Herr Kapitän!’’
Seeing Ulrich von Wittgenstein arriving at a run in the control room, Otto signaled him to come to him at once.
‘’Ulrich, I want you at the torpedo fire control station. Our first salvo will be with electric eels only: I want our first salvo to come as a complete surprise to the Americans. We will also use a time on target attack procedure. Have the torpedoes set to arm after a hundred meters, with running depth set for five meters, so that they could strike under the armored side belts of the heavier enemy ships. We will then reload with electric eels in the bow tubes and G7a eels in the stern tubes, set to a depth of three meters: we may be tangling with a few destroyers by then.’’
‘’Got it!’’
With his officers and men now getting busy implementing his orders, Otto looked back at the chart of Mamala Bay, planning in advance his incoming moves and the enemy’s possible counter-moves.
06:25 (Hawaii Time)
Command bridge of the aircraft carrier U.S.S. SARATOGA (CV-3)
Sailing down the entrance channel of Pearl Harbor
Rear-admiral Frank Jack Fletcher was feeling both morose and pessimistic this early morning as he watched his Task Force 61 leave Pearl Harbor just after Sunrise. For one thing, the amphibious operation that his task force was due to support in the Solomon Islands, down in the South Pacific, was in his mind not ready to go, due to the insufficient supplies and reserves in place. Also, his task force was originally supposed to be much more powerful but, thanks to painful losses during the last few months, most of them incurred in the Atlantic, it was now short by one carrier, one battleship, three heavy cruisers, one light cruiser and over half a dozen destroyers. He had strenuously argued with Admiral Nimitz that more time was needed to gather enough ships and supplies for the operation but Nimitz had replied, somewhat correctly, that any more time taken would also be more time given to the Japanese to establish a solid foothold in Guadalcanal and the rest of the Solomon Islands, thus putting Australia within range of Japanese land-based planes. Fletcher had thus given up on his opposition and had done the best he could to prepare his limited force for combat. This morning, he had sent three of his nine destroyers out of the harbor in advance of the rest, so that they could start sweeping Mamala Bay at once for any possible trace of that damned U-800, which had seemingly managed to scare to death Washington. His six remaining destroyers were now coming out and forming two widely-separated parallel columns that would sandwich the heavy units of the task force, with the battleship SOUTH DAKOTA in the lead of the central column. Behind the battleship were the SARATOGA, followed by the carrier ENTERPRISE, the heavy cruiser MINNEAPOLIS and one fleet oiler. With the addition of numerous patrol planes that had swept over the bay at dawn, Fletcher was at least confident that his task force would safely sail away from Hawaii.
On the GRIDLEY-Class destroyer U.S.S. BAGLEY, Petty Officer First Class Samuel Porter was busy operating his ASDIC set, sweeping methodically a ninety degree arc ahead of his ship with his directional sonar head, firing an acoustic ‘ping’ every few seconds and then listening for possible echoes. His ASDIC set was a far cry from the panoramic sweep passive/active sonars that would enter service in the decades to come, being short-ranged and being subject to getting false echoes bouncing from a number of things, including sea bottom features, whales and thermal layers. The ASDIC also was next to useless against surfaced targets, which was why German submarines so often attacked on the surface at night. It took an experienced and efficient operator to be able to get the best from such primitive equipment, but Sam believed firmly that he was such an experienced man. However, he was now being handicapped by the stubbornness and technical ignorance of his captain, who refused to understand that rushing out of Pearl Harbor at twenty knots in order to stay in formation with the two other destroyers of the advance screen would render his ASDIC set next to useless.
‘’I might as well be sending love telegrams to whales right now.’’ Sam thought to himself. It was in fact far from being the first time that improper ship tactics had cut on the efficiency of their anti-submarine searches.
As Samuel was scanning at the starboard limit of his search arc, a weak return echo suddenly made him stiffen up. That echo, about 300 meters distant, was however much weaker than that he would have expected from a submarine. Unfortunately, the high speed of his ship now prevented him from sending a confirmation ping on that azimuth. Looking at the chart of the Mamala Bay displayed to one side of his station, he saw that the weak echo had been located near the known limits of the defensive minefields of Pearl Harbor. Maybe he had pinged an isolated mine that had been misplaced away from the rest of the minefield. That would certainly explain the weak return echo. Somewhat reassured, Samuel then continued with his laborious scanning.
On the U-800, Hans Bock blew air out in relief as he looked at Gerhard Hoepner.
‘’Wew! That American nearly nailed us with his ASDIC set. Fortunately, he is now past us.’’
‘’Yeah, and the destroyers following it are also going too fast to be able to hear much themselves. Soon we will be able to bypass those destroyers by the rear and enter their formation undetected. Then, they will learn what it means to be rear-ended by Kapitän Kretschmer.’’
Both sonar operators then chuckled briefly at the joke made by Hoepner.
On the U.S.S. SARATOGA, Rear-admiral Fletcher was standing on the starboard open wing of the command bridge, watching the ships of his force, when the whole 47,700 ton aircraft carrier shook violently, while a tall geyser of water rose along its starboard flank. Two more torpedoes, as they could only be torpedoes in Fletcher’s mind, shook again the carrier in quick succession. Severely shaken and with his ears ringing, Fletcher picked himself up from the deck to look over the bulwark and down at the hull of his carrier. More explosions however made him snap his head aft, towards the U.S.S. ENTERPRISE, which was following about 400 meters behind. He banged his fist on top of the bulwark out of anger when he saw that his second carrier had also been torpedoed. Two more geysers erupted, this time against the starboard flank of the battleship U.S.S. SOUTH DAKOTA. The mission of Task Force 61 was now over even before it could get fully to sea! Looking out at the destroyers of his protective screen, Fletcher saw that they were now reacting with commendable speed, albeit belatedly, to that attack. Forming up in two successive lines abreast, the nine destroyers soon started throwing in the water dozens of depth charges in and around the spot presumed to contain the enemy submarine. That was when the first damage reports started arriving on the bridge. Fletcher was listening to one such report when a series of powerful detonations in the distance made him snap his head around. What he saw made him swear to himself: one of the destroyers, passing over the edge of the submerged defensive minefields, had made the mistake of throwing depth charges amidst the mines moored to the bottom. Those depth charges had in turn triggered a chain reaction among the mines, making them exploded one after the other in quick succession. The unlucky destroyer was now being mangled and ripped apart by the series of powerful underwater explosions, sinking quickly in minutes. That in turn made more mines explode as the hull of the destroyer sank down to the level of the moored mines and made contact with them. Just as Fletcher thought that things couldn’t possibly get worse, four more torpedoes slammed home, two against the SOUTH DAKOTA and two others against the heavy cruiser MINNEAPOLIS. Fletcher paled when he realized that the torpedoes hat hit the port side of his ships this time: that damn submarine had already crossed over to the other side of his force, demonstrating an incredible submerged sprint capacity. The worst part was that the destroyers that were supposed to cover his port flank were presently on his starboard flank, busy killing fish by the thousands by dropping dozens of depth charges over a now empty spot.
‘’DAMN IT! RADIO TO OUR DESTROYERS THAT THE ENEMY SUBMARINE IS NOW ON OUR PORT FLANK!’’
It apparently necessitated a few minutes to his destroyers to get that information, as they took a seemingly long time before starting to turn around to come back towards the wounded carriers. The crew of the SARATOGA was now fighting hard a serious fire in its aircraft hangar caused by broken aviation fuel lines that had then ignited. Fletcher could feel the intense heat even from up in the bridge superstructure of the carrier. As for the ENTERPRISE, while not on fire, it was starting to take an alarming list to starboard.
Things worsened yet again as the rushing destroyers were finally about to go around the limping heavy units of the force. Eight more torpedoes struck home, three each against the ENTERPRISE and the SARATOGA and two against the MINNEAPOLIS. Fletcher was wondering why the battleship SOUTH DAKOTA had not been targeted this time when four more torpedoes exploded against the port flank of the 44,000 ton warship. With a last shudder, the recently commissioned battleship rolled over and capsized, dragging over 2,300 men to their death. There was a moment of stunned silence on the bridge of the SARATOGA, as all the men present stared with disbelief at the now overturned hulk. The heavy cruiser MINNEAPOLIS soon sank as well, its stern blown off. The rapidly increasing list of his carrier then reminded Fletcher that he himself was in real danger of dying, along with many of the 2,900 crewmembers of the SARATOGA. He was about to distribute a new set of orders when the hundreds of aircraft bombs and torpedoes crammed into its aviation ammunition magazines, filled to capacity, started exploding, set off by the burning aviation fuel. A gigantic explosion tore the big aircraft carrier in two and sent up a huge mushroom cloud of flames and black smoke, along with hundreds of tons of metallic debris. That mushroom was in turn seen by the whole population of Honolulu and by the men stationed in Pearl Harbor, including Admiral Nimitz.
The now positively enraged captains of the American destroyers didn’t think about slowing down and thus giving a chance to their sonar operators to be able to work their sets properly. Instead, they rushed over the zone where the torpedoes had to have been launched and dropped more depth charges, rapidly emptying their anti-submarine magazines. Again, they arrived too late, as the U-800 had moved closer to the remaining aircraft carrier, the ENTERPRISE, while reloading its tubes. The captains of the remaining eight destroyers finally regained some tactical sense when the ENTERPRISE finally rolled slowly to one size and sank, victim of massive flooding from its six torpedo hits. Slowing down at last and performing proper ASDIC sweeps, they were unable to find any submarine, as if none had ever been present. However, those sweeps had been seriously hampered by the cacophony of underwater noises created by the breakup and sinking of the two carriers, one battleship and one heavy cruiser. Completely discouraged, the crews of the destroyers were about to initiate rescue operations to save the hundreds of men now swimming on the surface of the sea or sitting in rafts when all hell broke loose again. Carefully aimed torpedoes started picking up in quick succession the destroyers as they were going at slow speeds towards the sites of the wrecks. By the time that the captains ordered their ships to accelerate again, four of their numbers had been hit, each by a well-placed single torpedo. Those four destroyers were unable to raise appreciably their speed afterwards, having to fight flooding and, in one case, a complete machinery shutdown. After a six minute-long deadly ballet, all of the eight American destroyers had been hit at least once, with two of them already sunk and three more slowly sinking, while the rest were in no state to fight. The belated arrival overhead of a dozen bomber aircraft finally gave some respite to the survivors, but the collection of fleet tugboats, minesweepers and harbor launches that then tried to come to help the rescue effort at sea was stopped cold when the two first boats to come out of the harbor channel blew up on powerful sea mines that were not supposed to be there. More time was wasted as minesweepers had to start hunting and clearing mines from the mouth of the entrance channel.
Aboard the U-800, now withdrawing towards deep waters at quiet speed, Lieutenant-commander Nagaoka fervently shook hands with Otto Kretschmer.
‘’Captain, this was a virtuoso display of submarine handling as I never saw before. With those two carriers sunk, you just helped the Imperial Japanese Navy restore most of its initial advantage in the Pacific.’’
‘’Well, it will also force the Americans to switch more warships from their Atlantic Fleet in order to replenish their Pacific Fleet, which means in turn less pressure on Germany in the Atlantic. Both of our countries are winners as a result of this battle.’’
‘’Quite true indeed, Captain. What do you intend to do now? Sink more ships around Hawaii?’’
‘’No! I have expended 64 torpedoes up to now during this mission, leaving me with only eight torpedoes. I intend to reserve those torpedoes for my self-defense during the rest of our mission.’’
Otto’s serious expression then changed to a devilish grin.
‘’However, I do have lots of 12.7 centimeter deck gun ammunition left.’’
22:12 (Hawaii Time)
Office of Commander, U.S. Pacific Fleet
Pearl Harbor
Chester Nimitz felt like a broken man as he sat, nearly prostrate, behind his work desk. Most of his morning had been busy organizing the rescue effort to save the men from Task Force 61 who could be saved. After sending a preliminary report on the disaster to Washington, he then had to deal with the avalanche of anxious and fearful telephone calls from grieving navy wives that had started to inundate the telephone switchboard of his headquarters. One rather heartless staff officer had proposed to simply cut off those calls. Nimitz’ response to that had been to relieve that staff officer on the spot and send him packing to somewhere in Alaska.
The noise of a powerful explosion not too far from his building, along with the shaking of his windows, made Nimitz jerk out of his chair and go to his windows to look outside into the night. The whole base, along with the civilian agglomerations around it, including Honolulu, was now under imposed night blackout curfew on his express orders. His eyes thus had no problems catching the flashes of light and flames that were visible in the direction of Pearl Harbor’s Navy fuel depot. He swore violently when he saw that twin explosions every six or seven seconds were sweeping the fuel depot, piercing the huge fuel tanks with hot shrapnel or ripping them open, with the fuel then gushing out by the thousands of gallons and catching fire. The fuel depot had been the one important target that the Japanese had neglected to hit during their faithful attack on December 7 of 1941. Now, someone was bombarding it with accurate and intense shellfire. The identity of that someone was also not very hard to guess.
‘’DAMN YOU, KRETSCHMER!’’