I posted this some time ago, but it´s nowwhere to be found any more. so here is my take of what could have happened if the US military had paid more attention to the known capabilities of the Japanese, instead of geuessing their intentions:
June 1941: Brig.Gen. Becker arrives on PH. He is on an inspection tour of the US´s bases in the Pacific and has caused considerable irritation inside the war department by sending several highly critical reports. His opponents figure out the best way to silence this insufferable prick is by … promoting him. MG Martin, CG of the Hawaiian air force is suffering from a severe ulcer condition, so MG Becker is choosen as his replacement. And he does something unusual, he´s making his plans based on the opponents known capabilities, rather than his perceived intentions.
- Threat identification and assessment:
Targets: First and foremost the US Pacific Fleet, secondly units protecting it.
-sabotage: Highly likely, but limited effects. Particularly the Fleet is safe from it.
-submarine attack: concerns the USN
-carriers based air raid: worst case scenario, not likely, but possible
Sabotage: Barb wire, lighting the perimeter, increased patrolling
Air raid:
-recon: Upon asking BG Becker learns the USN is concentrating its limited number of PBY´s in the southeast, therefore B-17 and B-18 are watching the northeast sector as part of their routine training ops.
-Dispersion of planes and use of camouflage, construction of dummy planes: The former makes sabotage easier, but the latter can be implemented without problems.
-readiness: 24/7 high readinesses is not possible. The timing of an attack has to be narrowed down. The main target of an air raid would be the Fleet. Analysis of Fleet movements show a month long patter of the Fleet returning on Friday or Saturday and never leaving PH before Monday. Logical conclusion: A hypothetical attack will occur on a Sunday.
Now USN carrier Admirals and pilots are being contacted to tell the Army how they would attack a major naval base. Answer: Keep your distance on D-Day minus one to avoid detection, steam at full speed to the target after dusk, launch planes at dawn.
The rest is simply math. Assuming the speed and range is Japanese CVs is similar to American ones an attacking fleet will be y mile out on D-1 and x mile on D-Day. Based on sunrise, estimated time to launch the planes and their speed and range the planes will hit the target z minutes after sunrise.
That brings up the question of how to attack a hostile fleet:
According to conventional wisdom B-17 and B-18 bombers are useful for anti-shipping mission, a theory MG Becker puts to the test. Old, slow USS Utah is bombed and bombed and bombed, but just 1% hits are counted. Even without AA-fire, fighter and ten more knots level bombers are obviously useless. Dive bombers are highly accurate, but unavailable. So the crew chiefs are asked to come up with a way to put bomb racks on the fighters. Several P-40B are “converted” and rigorously test the various “designs”. Tests with racks for 500 pounders fail, but a centreline bomb rack for a 300lb bomb is a success. The conversion and intense bombing training starts in September and intensifies throughout the fall.
While Japanese-American relations steadily deteriorate, the strength of the Hawaiian Air Force grows slowly, but readiness and versatility has significantly increased. Other notable changes are more AA-guns being stationed on the airfields and the radar units and the Information Center are now under HAF command.
December 6th, evening:
The regular fight of B-17 and B-18 on recon returns. The search of the northeast approaches has come up negative.
December 7th, before dawn:
Several O-47B take off to be position for a search 150 to 200 miles off PH at dawn.
Disgruntled airmen start moving the planes off the runway, where they have to be put at night because of anti-sabotage measures ordered by (stupid) higher ups(=Gen. Short). The fuelling and arming starts at dawn. Two fighters per squadron are kept ready for immediate take off; two more are ready with the pilots allowed to remain in the officer’s mess. The men are woken up. At weekends only half of the squadron’s personnel get´s to leave the base in the evening, the rest has to remain until the party goers have sobered up.
December 7th, dawn:
The fighter squadron´s AA-weapons are being manned.
An O-47B actually finds Kido Butai, the observer send a message, but it arrives only scrambled and before it can be repeated the Japanese CAP get´s the slow observation plane.
06:00 hrs: the recon plane launched by cruiser Chikuma is overlooked by radar operators.
06:15 hrs: two radar station report contact in the south, call the Information Center. Lt. Kermit Tyler takes and the call, and as it fits the profile alerts Wheeler: Incoming unidentified airplanes! A pair of P-40B takes off to investigate.
06:45 hrs: three other radar stations pick up a contact in the north A pair of P-36A fighters are send to investigate
07:20: The P-36A make contact and report … more than 100 Japanese airplanes!
07:22: The 18 fighters on standy-by take off, everybody else is running to their planes. Fighter pilots to intercept the enemy, bomber pilots on Hickam to get their planes out of harms way. Coast Artillery AA-units and the USN are informed of the confirmed presence of Japanese warplanes near PH. ETA: no later than 08:00!
With at least 100(out of 138 total) P-40(99) and P-36(39) in the air by 07:50 the Japanese run the gauntlet. Although more manoeuvrable, the Zero´s pilots are shocked at the little damage their 7.7mm machine guns on the P-40s(20mm guns are inaccurate and have little ammo). And being outnumbered by nearly 3:1 means they can´t stop all attackers anyway. As a result the dive and torpedo bombers suffer the first losses. But once they reach the port it gets really ugly. Every AA-gun is cocked and loaded and the planes fly into a hailstorm of bullets. And they have to do so at a lower speed and at a lower altitude than on the open sea, because otherwise the torpedoes would sink to deep and hit the bottom of the shallow port, regardless of technical modification on the torpedoes. The result of the attack is devastating, but it´s the attacker who are devastated. The combination of low speed and altitude makes them the perfect target and the AA(weak by 1944 standards) blows them out of the air one by one.
USS California is hit once and stays afloat, Oklahoma is unlucky, she’s hit three times, starts to capsize but counter flooding means she settles on her keel. West Virginia is hit twice and stays afloat. Nevada was the only BB to get under way and has already left the port, she escapes unharmed. The remaining BBs suffer minor damage from bombs dropped by the second wave.
The first P-40´s landing for quick ammo and fuel refill are being held on the ground. In the Information Centre Lt. Tyler has remembered the O-47´s garbled message and since the time and the vector match that of the Japanese planes it´s highly likely that plane found the attackers. The IC orders all B-17s to search this and the neighbouring sectors, while the P-40´s are turned into “B”-40s.
20 or so B-40s take off even before the second wave arrives and fly into the area the O-47 vanished. Once the B-17s confirm the position they increase the speed. In the meantime B-17s distract the Japanese CAP by making ineffective but uninterceptalbe bombing runs at high altitude. As a result the P-40´s make their approach undetected, they go into a short dive to pick up speed and execute a textbook high speed glide bombing attack on tow CVs. Shokaku is hit five times, Ziukaku six times. The decks and hangars are destroyed, but the light 300lb HE bombs can´t penetrate the armoured hangar deck and no major fires are started. The B-17 attacks have delayed the landing of the first wave, so that the plane´s fuel tanks are almost bone dry and the fuel lines remained closed. The P-40s escape without any losses.
Meanwhile the second Japanese wave has left PH and a second American wave is made ready. Let´s be pessimistic here. 110 of the 129 fighters were ready on Dec 7th. 60 have been lost or damaged so they can not fly, at least not 200 miles over the ocean, so the second wave is around 30 planes strong and a mixed force of P-36 and P-40s. All planes get bombs, but some are designated fighters and they will jettison the bombs in case the Japanese CAP intercepts them. Which they do! But the 14 B-40s are well enough protected to make it all the way to Kaga, who gets nine or ten hits in her superstructure, including one 1000 pounder dropped by a Navy SBD from USS Enterprise that causes extensive damage and knocks out one of her engine rooms. The fighters, especially the poorly protected P-36 have suffered badly at the hands of the CAP.
The first- now third- wave is not able to find the Japanese again and attack Kaga instead, or rather the two CAs escorting her. She is not considered a worthy target, because she is a smoking, limping cripple. The P-40 pilots are sure Navy will get her anyway. But the Navy does not get her. Just when the P-40 end the attack, Kaga partly vanishes behind three big water columns. A sub? No a B-18 Bolo! The pilot has heard about all the failed high altitude attacks, so he concludes he needs to go a bit lower. While the Japanese are distracted,
Capt. William H. Kelso junior takes “California Girl” down to 300 feet, sneaks up to Kaga and put three 1,000 lb bombs an arms length away from her into the water. To his surprise Kaga stops, lists and capsizes – the bombs have detonated so close to her hull, they have ripped her open like torpedoes.
The search by Lexington and Enterprise for the remaining CVs is unsuccessful. Eventually it´s broken off west of Midway and the CVs are ordered to continue to Wake. The 18 Vindicator dive bombers meant for Midway and a dozen fighters are to be dropped of on Wake. The whole operation is uneventful, but it saves Wake. When the unescorted Japanese bombers attack Wake on the next day, Vindicators on patrol see them, warn Wake and 15 instead of three Wildcats intercept the bombers. A few make it home they report something far more terrifying than an 80% casualty rate: The attackers had NAVY markings!
Tokyo is informed and the HQ immediately cancels the planned invasion of Wake, the retreating CVs are ordered to avoid Wake, because US carriers are already waiting for them there. Saratoga and the relief convoy will not be later than in OTL, so the considerable reinforcements will make it to Wake undisturbed and after that any Japanese invasion attempt fails by default. They just don´t have the infantry to beat that many Marines and they don´t even have a clue they don’t have enough infantry.