The airplane that did the most to turn the tide of the war.

[MarkinTex]

No offence but that is just American revisionism. Germany would have been defeated either way since Operation Barbarossa was not going to succeed, with or without American war materials. Sure American war materials certainly helped both the Soviets and British, but it was not the deciding factor.

A big part of why Barbarossa wasn't going well (and why the Brits had been able to hang on till '42) was Lend-Lease, and if the US hadn't entered the war, the Brits would have never been able to do anything in North Africa which means no Italian invasion, and would not have been able to successfully invade France. The Eastern Front might have ground to a standstill, which would have meant that the Germans and Russians would have come to a separate peace just like they did at Brest-Litovsk in the first war, which would have freed up Germany to go after Britain.

 

[MarkinTex]

Americans/Soviets = Almost impossible since the Americans would not really have any way of attacking the Germans, or supplying the Soviets.

Not necessarily so. The UK had handed over Iceland to the US for just such a contingency, and from there we could have at least retaken the UK, and we could have supplied the Soviets from Alaska.

 

[Navalwarrior]

If the Japanese had not lost four carriers (well, maybe 3) at Midway, I don't think there would have been a Battle of Santa Cruz, because there would have been no American offensive at Guadalcanal. The Guadalcanal offensive was only possible because the shift in naval strength thanks to Midway. In the early summer 1942, The Saratoga came back from repairs in the States and the Wasp transferred from the Atlantic. This gave the Americans 4 carriers with which to conduct the Guadalcanal offensive. (Of these 4 they soon found it difficult to keep more than 2 on station at the same time.)

If Midway had been a draw or an American defeat in terms of numbers of carriers lost. The USN would likely have kept its remaining carriers busy defending the sea lane to Australia with maybe an occasional raid. Without SBDs taking out flight decks at Midway, the war against Japan would likely have been in a holding pattern for a year or more.

Ironically, I don't think the ultimate result would have been much different. The new fast carriers of the Essex and Independence class, with their newer aircraft models would still have been able to establish air supremacy wherever they congregated by early 1944. The Marianas would still have been assaulted in mid-1944, and the US would likely have won the war before the end of 1945.

Probably the biggest change if there had been no Guadalcanal or Solomon Islands campaign is the crucial role of the submarine fleet would come into sharper focus. Japan could assault Midway, but they would have had a hard time taking it, and an impossible time holding it. The submarines would be able to operate from Midway and Australia regardless of the outcome of the Battle of Midway.

Resp:
Agreed. All good points. Keep in mind that at one point in the Pacific War the USN borrowed a Royal Navy Carrier to operate from. Also, when Adm King flew out to California to converse with Nimitz in Dec '41, he told Nimitz 'we aren't defending anything! I want you to Attack, Attack! This was when California was arming/fortifying the West Coast against attack. So the USN stayed aggressive.
As far as US subs are concerned, initial boat Skippers were bred in the 1930s . . . and weren't aggressive enough, often returning to port with one or two torpedos fired. A lot of these Skippers were immediately replaced with younger, more aggressive men who got results. Warfare changes things.

 

[buffnut453]

A big part of why Barbarossa wasn't going well (and why the Brits had been able to hang on till '42) was Lend-Lease, and if the US hadn't entered the war, the Brits would have never been able to do anything in North Africa which means no Italian invasion, and would not have been able to successfully invade France. The Eastern Front might have ground to a standstill, which would have meant that the Germans and Russians would have come to a separate peace just like they did at Brest-Litovsk in the first war, which would have freed up Germany to go after Britain.

There are SOOOOO many incorrect statements in that post. Firstly, Britain didn't "hang on" until 1942 courtesy of Lend Lease. Lend Lease only started in March 1941 and, frankly, was a pittance compared to the military production occurring in the UK. Britain grew stronger militarily from the low point of May 1940 onwards...so please explain how Britain would have capitulated without Lend Lease.

As to Britain doing nothing in North Africa without Lend Lease, again please explain that comment. British and Commonwealth forces had already effectively defeated the Italians, forcing Germany to engage in early 1941. Tobruk, a vital turning point of the Desert War, took place Apr-Dec 1941 but Lend Lease shipments only really got going towards the end of that period and so had little impact on the battle.

 

[buffnut453]

Not necessarily so. The UK had handed over Iceland to the US for just such a contingency, and from there we could have at least retaken the UK, and we could have supplied the Soviets from Alaska.

You're seriously suggesting a naval invasion from Iceland to retake the UK had the latter surrendered? I'd love to know exactly how that would be carried out. Also, the UK didn't "hand over" Iceland. An agreement was reached between the US and Iceland for the US to take over defensive responsibility in return for supporting Icelandic independence after the war.

 

[parsifal]

(C-46 over The Hump)

C-46 suffered from a series of mechanical and design failures. ATC crews referred to it as the "flying coffin". Other names given to it in the CBI by its crews were "The Whale," the "Curtiss Calamity," and the "plumber's nightmare". Until the removal of the electrically controlled pitch mechanism on the propellers, it could not carry full load over the hump and could not remain airborne with anything above 35000lbs payload. It did eventually do well, but a bit rich to call it "outstanding from the getgo. lacement of the

 

[parsifal]

A big part of why Barbarossa wasn't going well (and why the Brits had been able to hang on till '42) was Lend-Lease, and if the US hadn't entered the war, the Brits would have never been able to do anything in North Africa which means no Italian invasion, and would not have been able to successfully invade France. The Eastern Front might have ground to a standstill, which would have meant that the Germans and Russians would have come to a separate peace just like they did at Brest-Litovsk in the first war, which would have freed up Germany to go after Britain.

Leand Lease had almost no effect on Barbarossa. Us aid to the SU up to the end of 1941 amounted to less than $20million dollars. Later on it did make a difference.

Youve also omitted from this cosy summation that had it not been for British intervention over US ASW efforts, the US would have been brought to her knees by the U-Boats. Youve forgotten a little known thing called the Tizard mission which provided a vital boost to US efforts in development of radar, or the co-operation to set up and build an engine called the "Packard Merlin" used to drive one of your more sucessful fighter. Little number referred to as the P-51 I believe.

Best assistance to the desert army was in its tank park. The Americans did provide a lot of assistance to the british in this regard, buts arguable that the british would "not survive". Looking at Alamein……

The old A9, A10, and A13's had finally been pulled from front line service. In their place, 216 British built Crusader II tanks stood ready for service at El Alamein. These tanks still mounted the nearly obsolete 2 pdr gun with some mounting a 3 inch howitzer for infantry support.

Crusader III had been uparmored and carried a 6pdr gun in its turret. At this stage of the war, this was the most effective ATG available to the British in quantity and the US tanks did not compare well in their anti armour capability in this respect. This was the end of the line for the Crusader as the turret would not mount any bigger gun. 78 of these were available for the battle.

The cheaper, faster to build, and more reliable Valentine tank had now completely replaced the Matilda in infantry support battalions. 194 Valentines served four infantry support tank regiments at El Alamein, all equipped with the 2 pdr and 6 pdr gun.

The Matilda was now retired as a front line tank but the hulls were used for various conversions. The Matilda CS was still used to support the Valentine tanks which did not have a CS version. The Scorpion was a field modified Matilda with the guns removed and a rotating flail fixed in front of the tank to detonate mines. 25 of these helped clear mines at El Alamein.

The Churchill made its first appearance in combat since the disastrous Dieppe landing with the new Churchill III with increased armor and a new 6 pdr gun. Six were sent to North Africa for combat evaluation and were sent forward against the Germans during the El Alamein offensive. They proved to be very resistant to damage and performed well enough that more were built and sent into the later Tunisia battle area.

Bishop self propelled artillery was deployed for the battle, and was the first British attempt at self-propelled artillery. A 25pdr gun was mounted in an armored box mounted on a Valentine Tank chassis. Slow and with a restricted elevation which limited its firing range, the Bishop still managed to serve the British cause through the rest of the North African Campaign and into Italy. 100 were deployed for the battle.

The M-3 Light "Honey" tank had debuted during Operation Crusader as a main battle tank and, although it had many pluses, it proved to be too light to stand up well against the heavy German tanks. 119 were still around for this battle and were used mostly in a light tank role. Later versions would continue to serve in this role in British armored formations until the end of the war.

The M-3 Medium "Grant" had also debuted during Operation Crusader and still served as an important battle tank at El Alamein with 170 present for duty. These tanks would serve through and into the Tunisia campaign but would be phased out as more Shermans became available.

After the fall of Tobruk, FDR ordered the 1st U.S. Armored Division to give up its new M-4 Medium tanks and send them immediately to the British in North Africa. The British named them "Sherman" and had 252 of them ready to go at El Alamein. These tanks were spread out to nearly all the tank regiments and performed so well against the German tanks that the Americans decided that they needed no better tank for the rest of the war. This flawed logic led to the Sherman not receiving a main gun upgrade until after D-Day. But at Alamein its ability to fire HE was a big plus.

Priest was the mainstay of British self propelled artillery. British tank buyers ordered several hundred of these self-propelled artillery vehicles as soon as they laid eyes on them. Priests were sent straight to North Africa (making the Bishop obsolete just as it was being deployed) and served the British Army from El Alamein until D-Day.

 

[parsifal]

And then I have one final question for our newly arrived American. Where were the Americans in 1939 when they were needed? Same place they were in 1914, and that's nowhere.

 

[Shortround6]

Leand Lease had almost no effect on Barbarossa. Us aid to the SU up to the end of 1941 amounted to less than $20million dollars. Later on it did make a difference.

Here we have some confusion. I am not sure what British aid to Russia was called, it tends to get lumped into "Lend Lease" but the British sent a lot of stuff to Russia in 1941 that was not paid for by the US. This rather points out that Britain was hardly just hanging on if it could afford to send Several hundred Hurricanes and several hundred tanks. Delivery of Bell Aircobras also started in 1941 did they not? And I am referring to the ones the British paid for. I will admit I have no idea who paid for the 1390 Canadian built Valentines that went to Russia but that was after 1941.

Youve also omitted from this cosy summation that had it not been for British intervention over US ASW efforts, the US would have been brought to her knees by the U-Boats. Youve forgotten a little known thing called the Tizard mission which provided a vital boost to US efforts in development of radar, or the co-operation to set up and build an engine called the "Packard Merlin" used to drive one of your more sucessful fighter. Little number referred to as the P-51 I believe.

Yes the British did help school the US in anti-sub warfare, something that a few US admirals didn't want to hear. However the US also set up the "neutrality patrol" on Sept 5th 1939 and it was bit more tipped to the British than to the Germans.

Roosevelts thinking on the Matter certainly pre-dates the German attack on Poland.
"Roosevelt had been an thinking of such a patrolling operation for several months. On 20 April 1939, for instance, he told the Cabinet that he wished to establish "a patrol from Newfoundland down to South America and if some submarines are laying there and try to interrupt an American flag and our Navy sinks them it's just too bad."7
Abbazia, Mr. Roosevelt's Navy, p. 62.
Getting the rest of the US to go along took a bit of doing. The US was transferring ships to implement the patrol in the fall of 1939 and over the next two years the "neutrality patrol" became a whole lot less neutral, taking over a fair amount of the escort work in the Western Atlantic which allowed the British to increase the number of escorts per convoy in the eastern Atlantic.

The Tizard mission did give a lot of good things to the US, but it is not like the US was a bunch of bumpkins sitting around with their thumbs up their butts.
experimental radar on the Battleship New York in 1938. It could pick up planes at up to 100 miles and ships at 15 miles. Six production sets were delivered in 1940. A bit behind the British to be sure but the Tizard mission did not GIVE radar as a whole or concept to the US.

The whole Merlin thing is a bit of a red herring. At the time the contract was signed the Allison was hardly a "proven" engine so yes the US got something. However the version that would go in the Mustang wasn't even running on a British test bench at the time. It would take two years before they tried to put a Merlin in a Mustang. US use aside from the Mustang was confined to several thousand P-40s. Packard built 26,759 of the single stage engines and US kept 3000 at most and perhaps several hundred under that.

The British (and I always mean the commonwealth even if I don't always type it out) did do a lot that the Americans don't give credit for and the US did screw up a lot of early designs of a variety of weapons, we were far from perfect.

 

[Navalwarrior]

Here we have some confusion. I am not sure what British aid to Russia was called, it tends to get lumped into "Lend Lease" but the British sent a lot of stuff to Russia in 1941 that was not paid for by the US. This rather points out that Britain was hardly just hanging on if it could afford to send Several hundred Hurricanes and several hundred tanks. Delivery of Bell Aircobras also started in 1941 did they not? And I am referring to the ones the British paid for. I will admit I have no idea who paid for the 1390 Canadian built Valentines that went to Russia but that was after 1941.





Yes the British did help school the US in anti-sub warfare, something that a few US admirals didn't want to hear. However the US also set up the "neutrality patrol" on Sept 5th 1939 and it was bit more tipped to the British than to the Germans.

Roosevelts thinking on the Matter certainly pre-dates the German attack on Poland.
"Roosevelt had been an thinking of such a patrolling operation for several months. On 20 April 1939, for instance, he told the Cabinet that he wished to establish "a patrol from Newfoundland down to South America and if some submarines are laying there and try to interrupt an American flag and our Navy sinks them it's just too bad."7
Abbazia, Mr. Roosevelt's Navy, p. 62.
Getting the rest of the US to go along took a bit of doing. The US was transferring ships to implement the patrol in the fall of 1939 and over the next two years the "neutrality patrol" became a whole lot less neutral, taking over a fair amount of the escort work in the Western Atlantic which allowed the British to increase the number of escorts per convoy in the eastern Atlantic.

The Tizard mission did give a lot of good things to the US, but it is not like the US was a bunch of bumpkins sitting around with their thumbs up their butts.
experimental radar on the Battleship New York in 1938. It could pick up planes at up to 100 miles and ships at 15 miles. Six production sets were delivered in 1940. A bit behind the British to be sure but the Tizard mission did not GIVE radar as a whole or concept to the US.

The whole Merlin thing is a bit of a red herring. At the time the contract was signed the Allison was hardly a "proven" engine so yes the US got something. However the version that would go in the Mustang wasn't even running on a British test bench at the time. It would take two years before they tried to put a Merlin in a Mustang. US use aside from the Mustang was confined to several thousand P-40s. Packard built 26,759 of the single stage engines and US kept 3000 at most and perhaps several hundred under that.

The British (and I always mean the commonwealth even if I don't always type it out) did do a lot that the Americans don't give credit for and the US did screw up a lot of early designs of a variety of weapons, we were far from perfect.

Resp:
Interesting. Any thoughts on how the war would have progressed if the US just fought in the Pacific Theater, since they were not a major player in Europe? I would like to hear your version of how the conflict would have progressed. Thank you.

 

[Shortround6]

I didn't say they (the US) weren't a major player did I?
If I did please point it out.
The war was almost six years long, one could be a 'minor' player as you put it for part of that time and medium player for a while and a major player for several years.

There was an awful lot of grey and shifting shades but a lot of people seem to want a hard edged, black and white answer. The US was either a hero or cowardly villain sitting on the sidelines. The Soviets would have either collapsed like a punctured balloon without aid or rolled over the Germans in 1944/45 with only the vaguest suggestion of help from the British Commonwealth and the US.
and so on.

The US sometimes gets too much credit for things it didn't do (supply large amounts of 100 octane fuel to the British in the BoB) and sometimes not enough for things it did do.

The same goes for other nations.

 

[Shortround6]

A bit more on the American "neutrality patrol" Some British warships objected to being shadowed when in the waters the U.S. said were part of the neutral zone (which at times extended hundreds of miles out into the Atlantic but the American ships gave position reports pretty much in the clear in english.

out of 85 German Merchant ships in the western hemisphere in 1939 only 32 made it back to Germany, of the 126 german merchant ships in the rest of the world nearly 100 made it back.
The Americans would shadow the German ships and give position reports in clear English. What happens when German merchant ship leaves the Neutral zone? British warship waiting for it.

In one case, the Liner Columbus left Veracruz, Mexico on Dec 13th 1939 under orders to run the blockade and get back to Germany. Two US destroyers, the Lang and the Benham trailed her for several days and then were relieved by the Destroyers Cole and Ellis. The destroyers gave position reports every 4 hours and at night ran with their lights on. After the liner passed through the Florida straits two new Destroyers relieved the Cole and Ellis and the Cruiser Tuscaloosa joined in. Finally 320 miles north west of bermuda on Dec 19th the British destroyer HYperion responded to the position reports, showed up and put two shots across the bow of the Columbus, which stopped, had most of her crew abandon ship and the captain and remaining crew set fore to the ship and scuttled it. The Crew was rescued and brought to the United States.

I would think that this was about as un-neutral as you could get without actually firing guns.

 

[michael rauls]

And then I have one final question for our newly arrived American. Where were the Americans in 1939 when they were needed? Same place they were in 1914, and that's nowhere.

I agree that it would have been a whole lot better if the U.S. had entered the war earlier. Perhaps in 39 as you point out but i don't think you can blame the American public for being a bit queezy about entering another multifaceted war with another one so close in the rearview mirror.

 

[michael rauls]

Something that goes against alot of popular perceptions is that by 1940 the British alone were outproducing Germany rather handily in most kinds of equipment.
So I have read anyway.

 

[parsifal]

SR

I don't know the dollar amount of aid to the Russians, but it was substantial.....six convoys worth (I can eventually get it right if I stop for a minute....). However, purely on a technicality, Barbarossa was meant to last 6 weeks.....it was definitely over by the end of November (and really a whole lot earlier than that). After Barbarossa, the main German offensive operation was "taifun". British help started to have an effect from late November, whilst Taifun was in progress. Its a bit of a w*nk really, but not much aid for Barbarossa. Fist British aid convoy left British controlled port end of September arrived mid October as I recall, but it took time to assemble tha equipment and teach the Russians how to use it

 

[parsifal]

A bit more on the American "neutrality patrol" Some British warships objected to being shadowed when in the waters the U.S. said were part of the neutral zone (which at times extended hundreds of miles out into the Atlantic but the American ships gave position reports pretty much in the clear in english.

out of 85 German Merchant ships in the western hemisphere in 1939 only 32 made it back to Germany, of the 126 german merchant ships in the rest of the world nearly 100 made it back.
The Americans would shadow the German ships and give position reports in clear English. What happens when German merchant ship leaves the Neutral zone? British warship waiting for it.

In one case, the Liner Columbus left Veracruz, Mexico on Dec 13th 1939 under orders to run the blockade and get back to Germany. Two US destroyers, the Lang and the Benham trailed her for several days and then were relieved by the Destroyers Cole and Ellis. The destroyers gave position reports every 4 hours and at night ran with their lights on. After the liner passed through the Florida straits two new Destroyers relieved the Cole and Ellis and the Cruiser Tuscaloosa joined in. Finally 320 miles north west of bermuda on Dec 19th the British destroyer HYperion responded to the position reports, showed up and put two shots across the bow of the Columbus, which stopped, had most of her crew abandon ship and the captain and remaining crew set fore to the ship and scuttled it. The Crew was rescued and brought to the United States.

I would think that this was about as un-neutral as you could get without actually firing guns.

American warships did indeed provide this sort of assistance, but i would have to check as to when that started. I do know that at the beginning the Pan American neutrality zone, for which these patrols were carried out, did not exist at the bginning but after River Plate the US forced aall the Soth American states to sign up for it .


There was still quyite a bit of blockade running going on the german side until early to mid '41. Even the Italians had a go at that. The closure of the ports to Axis traffic was a fairly spongy affair.....often German flagged merchantmen entered US poprts under flags of convenience.

All those shenanigans ended abruptly but i forget exactly when and for what reason

 

[Conslaw]

You forget that the RN has armoured carriers, one of which actually served with the USN for a short time. The RN at this time was the largest navy in the World until US naval construction got underway.
HMS Victorious (R38) - Wikipedia

You are absolutely right that the HMS Victorious was sent to the Pacific in 1943 and served alongside the USS Saratoga for a crucial period between the time the Enterprise left for refit and the new fast carriers were ready for duty. The Victorious and Saratoga were mainly held in ready reserve incase the Japanese fleet went on a large offensive, which they did not.

 

[Conslaw]

Whether WATCHTOWER would be delayed is in no way dependant on how many Japanese carriers were lost. What made WATCHTOWER possible was a combination of several factors, none of which had anything to do with the loss of Japanese flattops

Planning for an offensive operation in the Solomons was well under way well before the victory at midway. It was approved and at an advanced stage of preparation, already having been approved by the Joint Chiefs. Some delays occurred whilst USS Wasp was lent to the Med TO for a spitfire reinforcement of Malta, and the repairs to USS saratoga was made urgent after the loss of the Lexington. Whilst on deployment with the British, the Wasp practised night carrier operations incompany with HMS Eagle.

Initially the plan was to take the island of Tulagi by assault and also occupy the essentially no-mans land of Santa Cruz. However on July 2nd, long range PBYs detected airfield construction on guadacanal and the targets were quickly adjusted

Enterprise Hornet and Saratoga were assigned as direct support units, and spent 3 weeks normalising and working up replacement air crews for the operation after midway. In this respect the results of Midway were relevant. Losses, or rather the absence of losses from the US carriers, along with the ability to draw in more reinforcements from the atlantic and Mediterranean, gave the US the numbers parity to attempt the operation with a reasonable chance of success.

After Midway, American intel was temporarily blinded by the Japanese changing their naval ciphers, this led to some minor adjustments to the US force components committed to Watchtower. Hornet was detailed to remain in Hawaiian waters and was replaced by Wasp . Wasp was unique in the USN inventory at the time in that she possessed some limited night strike capability in her air group, and I have no doubt this influenced the decision to insert Wasp in place of Hornet into the operation. Further, Wasps air group was made more effective by the embarkation of TBFs into the CAG, the first USN carrier to be brought up to strength with this new type. She also was considered better value with her F4F-4 fighters over the older more clapped out F4F-3s equipping the hornet. The amphibiouis operation was delayed by severe engine room troubles aboard the Wasp, which had not been fully resolved until the end of July.

In overall command was adm Frank j Fletcher, a much maligned individual in history but still very cautious in this operation.

The operation would still likely have failed but for the fact that the air assets based at Rabaul were fully occupied at Milne Bay and supporting the attacks across the owen stanleys. Allied resistance at Moresby in particular was occupying the full attention of the Japanese . If this had not been the case, chances are the Japanese would have inflicted far heavier losses on the invasion fleet

Despite being in excellent shape, TG61.1 under fletcher made the inexplicable decision to withdraw the carriers on the evening of 8th August. I get the impression that his caution was due to the intell blackout afflicting the USN at this time. The UsN had no idea of the whereabout of Combined Fleet, and were still very wary of its potential......the USN were under no illusions at that time that they needed to pay healthy respect to IJM capabilities still. The people who needed to know, knew that the loss of IJN cartriers at midway had virtually no effect on IJN fleet capabilities in August. If the IJN chose to commit, they could do a lot.


Some acknowledgement ought to be given to the role of the CVEs in WATCHTOWER. Though incapable of affecting the large scale sea battles, the arrival of these small carriers freed the USN fleet carriers from any need to provide ferryinh services to the island in later parts of the operation.

Regardless of whether the Japanese lost carriers or not at Midway, the operations in the Solomons were locked in to occur. The Japanese, with their dwindling carrier air fleets were simply not in a position to respond by then...…...they could not afford logistically to keep their carriers so far forward for a start. The carriers could be based as far forward as Truk and that was about it really.

Parsifal, let's take the hypothetical that neither the IJN or the USN lost any carriers at Midway, and plane and aircrew losses were minor, do you think the US would still have undertaken Watchtower in the late summer of 1942 even with the possibility of facing 6 first line Japanese carriers with experienced aircrew? If so, then the battle that was historically the Battle of the Eastern Solomons would have been a real slugfest, with potentially 6 Japanese carriers against 4 or 5 US carriers.

 

[Navalwarrior]

Resp:
My grandfather graduated from the USNA in 1921. However, the Academy did not equal a College degree . . until the 1950s, when he received notification/paperwork giving him a Diploma as a full college graduate. The Academies were considered 'trade schools' at the time.

PS.
I acquired my Grandfather's USNA yearbook, 'Lucky Bag' when he passed away in 1974. However, it wasn't until the early 1990s that I took the time to look through the book in detail. I noticed that above each photo he had written in ink the dates of his classmates promotions. It took some doing for me to understand what the last notations meant. Having resigned his Commission in the late 1920s due to no action (peace time officer), he also followed their WWII history.
These last notations noted posthumously awarded the M of H, died during Bataan Death March, MIA, PoW, KIA, ship sunk, etc. In 1943, he tried to enter the Navy, but was told he was too old at age 43. So he entered the Army as a PFC and was sent to the Pacific, where he worked in supply. My assessment is that he just couldn't sit out the war,

 

[parsifal]

Absolutely. . And that's not just me blowing out of certain parts of my anatomy. Planning for a counterstroke had been in the works since the Doolittle Raid. initially Macarthur had wanted an immediate invasion of New Britain, which was supported by his boss, Gen Marshall, but rejected by the Navy, Gradually a plan evolved such that by about the time of Coral Sea it had progressed to a recognizable "WATCHTOWER' like plan to invade Tulagi and Santa Cruz (Gavuto). Later still it was changed again to Guadacal when recon showed an airfield under construction on the island.

The victories at Coral sea and midway brought more of the doubters in the USN on board with the plan, but had little to do with the decision in the first place

The USN was well aware of IJN problems in the supply of aircrew. Even in quiet times they were losing far more naval aviators than were being received from the training schools. Up to june 1942 ive read the IJN had received about 100-150 additional pilots (depending on your source) since the beginning of December 1941, for both land based and carrier based air assets. That wasn't enough to even keep up with normal peacetime wastage let alone a nation at war. Even as early as April, Yammamoto was communicating with IGHQ on a regular basis, complaining about the falling standards in crew training. The Japanese were even at that stage being forced to abandon their desire to replace elite aircrew lost with new ly trained elite aircrews. After June 1942, the numbers of aircrew increased in the IJN, initially roughly doubling in monthly graduations (to about 30 per month), but this still wasn't anywhere near enough. And even at 30 per month the quality of those replacements was far short of the prewar standards.;

You guys would have a better idea of new aircrew arrivals for the USN, than what I do, but it was far greater than 30 per month. From mid 1942, the allies wanted to increase the pressure on the Japanese. Increase the pressure and the attrition rate goes up, increase the attrition rate, and the Japanese go into an even steeper crisis than they already are.

The other thing that gave the allies confidence, was distance. They knew that the closest that the Combined fleet could be based with supply on hand was Truk. This was at least a weeks sailing time from Guadacanal. If the Combined Fleet tried to base forward of Truk, where her prewar oll stocks were located, massive pressure would be brought to bear on her dwindling tanker fleet. Japan was already short of oil transport capability and needed just about every one she could get her hands on to bring oil home to the Home islands. It was a reasonable assumption to make that the Combined Fleet would not be able to interfere with the invasion for some weeks, which is exactly what happened historically (not counting the response by mikawas locally based cruiser forces at Rabaul).