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Alterate History: BIplanes & Battleships

The era of battleships overlapped the era of biplanes from shortly before World War I until maybe early1942, when all of the major combatants except to some extent Italy had phased out biplanes, and battleships were increasingly relegated to a secondary role.  The self-imposed rules of this exercise: find scenarios that lead to battles involving either battleships or biplanes (or better yet both) in a prominent role.  To make things more difficult, we’ll rule out shore bombardment scenarios for the battleships.

Scenario 1: The British send an aircraft carrier to Singapore along with the battleship and battle cruiser.  They intended to, but didn’t because the one that they had allocated ran aground in a freak accident.  The admiral in charge was an old school “planes can’t sink battleships” kind of a guy, so he didn’t insist on a replacement, though an old carrier Hermes was available.  Let’s say Repulse and Prince of Wale do have a carrier, or maybe even  two—a modern one plus the Hermes, with them.  That’s probably enough to keep the Japanese air attack from sinking the British capital ships on December 10, 1941.   The Japanese carriers were initially off in the Central Pacific returning from the attack on Pearl Harbor, along with two of Japan’s 10 battleships.  Japan’s super battleships were not available yet.  The Japanese had two battleships of the Kongo class in distant support of their invasion of Malaysia.  The other six were screening against any US attempt to reinforce the Philippines or were in reserve.  These were relatively short-range ships and most of Japan’s refueling capacity was tied up supporting the force that attacked Pearl Harbor, so the Japanese would presumably be reluctant to get those ships too far away from home, though they can if necessary.


The Japanese can’t let two British battleships run around cutting off their supply lines to Malaysia and doing fire support for the defenders for the kind of time it would take for the Japanese carriers to get back to the area.   The logical force to go after the British were the two Japanese battleships covering the invasion.  So we have a battle between two forces of two capital ships each.  Figure that Japanese land-based airpower and the British carrier(s) pretty much cancel each other out.  So we get an old fashion Battleship slugfest.  Who would win?   The  Prince of Wales would have had somewhat more firepower than the Japanese battleships.  The Repulse would be roughly comparable in firepower but weaker in armor.

If the British lost, they would presumably lose the two ships they lost historically, plus possibly as many as two aircraft carriers.  What would  that do to the rest of the British war effort?  The Hermes was sunk by the Japanese in their raid into the Indian ocean in early 1942, so probably not much change there.  Losing the other aircraft carrier would have some impact.  Hard to know what.

If the British won, they would get an initial morale boost, and put a serious crimp in the Japanese timetable for taking Singapore.   They would also probably draw the attention of the Japanese carriers at some point.  The carriers and tankers would probably have to stop back at the home islands to refuel rearm and refit after the long voyage to Pearl Harbor.  If the initial two Japanese battleships are out of action, I suppose it its possible they could send  their six reserve battleships into the fray.  Before the disaster on December 10, the British had intended to reinforce their two initial capital ships with additional forces.  They sent four old battleships and one new fast one to the Indian Ocean, as well as an aircraft carrier.   Depending on how long it would take to get the Japanese carriers into the fight, and how long it would take the British to get additional battleships to the area we might be able to squeeze in one last battleship slugfest between the rest of the Japanese battle line and three or even seven British capital ships.  It would be interesting to see how that played out.   However it worked out, whatever forces the British committed would be in grave danger once the Japanese carriers entered the area.  Anything that didn’t run  would probably get sunk.  Still, it would be interesting to see how a Japanese/British battleship fight would play out.

Scenario 2: The British Abort the Channel Dash –In February of 1942, two German battleships (sometimes classified as battle cruisers due to their comparatively light guns), Scharnhorst and Gneisenau,and a heavy cruiser,succeeded in making a dash through the English Channel with only minor damage.  They were undetected for 12 hours after leaving a French port in which they had taken refuge after doing some commerce raiding.  The British navy was humiliated, though in the long-term the British were better off with the ships back in their home waters.  What if the plan for the dash had been detected early enough for the British to bring some of their own battleships in to intercept the Germans.?  The Germans would have been outgunned, but their ships were well-armored and they did have considerable airpower to bring to bear in the battle.  If the Germans succeed in sinking one or more British capital ships and still get away, it stretches British naval power even more thinly.  If the British manage to sink one or both of the German ships without losing any of their own, then that frees up considerable sea power for other uses.  The Italians might find themselves having a bad day in the Mediterranean, or the Brits might decide to send more battleships to help control the Indian Ocean.  If the Brits try to directly fight the Japanese carrier raid into the Indian Ocean, they would probably lose whatever ships they sent there, which would put them back about where they started.

Scenario 3: Ambush at Pearl Harbor – How can we turn carrier airpower’s single biggest victory over battleships into a battleship versus battleship matchup?  Not easily, but let’s try it.

Let’s say that FDR and company find out or figure out in detail what the Japanese are planning at Pearl Harbor.  Maybe they crack the proper codes early enough.  Maybe they tap into a well-placed spy.  Maybe Kimmel and Short’s local intelligence people just do a brilliant job of analyzing Japanese intentions.  In any case, US commanders in Oahu are pretty sure the Japanese will be launching an air raid on Pearl Harbor sometime between November 28 and December 10.  They suspect it will happen at dawn, and they have December 7 marked down as the most likely morning because that’s when they feel that the fleet is at its most vulnerable and there is a full moon the night before, which would make predawn takeoffs and preparations less risky for the Japanese.   They realize that the short-legged Japanese destroyers and cruisers escorting the carriers cannot make the trip to Oahu without refueling, so they assume that Japanese tankers have to be lurking within a few hundred miles of the taskforce.  

Kimmel and Short quietly do what they can to prepare for exactly that attack within their orders not to alarm the civilian population.   Army anti-aircraft guns are unobtrusively manned—maybe with the gunners playing the role of additional security, and are stocked with ready ammunition.  Fighter pilots are ready to take off on a few minutes warning.  Radar operators are told to remain on duty during the hours between dawn and about 10 am and are given a direct line to army and navy officials authorized to scramble planes and sound a general alert.  The navy makes sure all watertight doors are closed and at least two or three of the battleships in the outer and more exposed row are ready to move if necessary on a few minutes notice.  A couple of destroyers are loaded down with extra anti-aircraft guns and heavy machineguns and put on standby with instructions to move to cover the path any torpedo planes would have to take to attack the battleships.   The two US carriers in the area are ordered to stay out of the harbor but be prepared to go after either the Japanese carriers or the tankers if the Japanese attack.   The navy doesn’t have torpedo nets, but they improvise a drill of moving target ships into the area torpedoes are most likely to have to travel. 

With those advance preparations, the US scrambles planes and mans antiaircraft guns shortly after the Japanese aircraft are detected by US radar.  The battleships with steam up move out of the harbor, while the rest begin getting up steam and get ready to fight from within the harbor.   The Enterprise is close enough to launch plane in support of the Pearl Harbor defense.  By the time the first wave of Japanese planes reach the harbor the sky is full of US fighter planes.  US seaplanes and bombers are searching along the radar plot to find the Japanese carriers, and tankers. 

So, what do you think?  The objective of all of this is to end up with at least some of the US battleships ready to go at the end of the attack—hopefully most of them, and as many of the top-notch Japanese pilots in the raiding force dead.  Sinking a Japanese carrier or two would be nice too, but that’s not all that important if the pilots flying off of them get deceased.

Historically the Japanese lost 29 planes and had 74 more damaged, many of which had to be written off.  Of the planes lost, 20 of them were in the second wave.  Presumably US anti-aircraft would pick up quite a few more kills in both waves if they had around an hour to get ready and were already on heightened alert.  Historically most if not all of the army anti-aircraft batteries didn’t get into action until the attack was over because ammunition was locked up to protect against sabotage.  The 50 Japanese torpedo planes would get really hammered under this scenario because they had to come in extremely low and extremely slow on the initial run.  In the absence of surprise they would probably have been nearly wiped out.  Let’s say that US anti-aircraft gets 40 out of 50 of the torpedo bombers, and another 30 of the rest of the first wave.  US fighters get maybe another 30, while losing at least that many planes.  That’s over half of the first wave, with most of the rest damaged.

Without the extremely vulnerable torpedo bombers in the second wave, the US would have to work harder to up the score, but there would only be 36 Japanese fighters to defend 135 bombers, including over 80 dive bombers.  I would say the US gets about half of Japanese planes—maybe 85 to 90, including cripples that crash on the way back to the carriers.  So overall the Japanese lose just a little under half of the planes and pilots they have in the six carriers, mostly bombers.  Figure that most of the remaining planes are shot up to the point of not being immediately flyable, and while the Japanese can still maintain an effective combat air patrol they have little offensive capability.

By now the US has located the Japanese carriers, and both the Enterprise and the army airforce launch raids on them, right on the tail of the second wave.  The Japanese combat air patrol over the fleet is strong enough to prevent serious damage to most of the carriers, but the Japanese lose more planes as the aircraft of the second wave get back to the carriers while the carriers are under attack and maneuvering at high speed.  By the time the US air attacks end, the Japanese carriers only one carrier is damaged, but the carriers have considerably less than half of their air arm left, and the bulk of that—especially the bombers--is unflyable.  Planes can be replaced eventually, but veteran pilots can’t.  The Japanese carriers are now a much diminished threat.   The US has also lost heavily in the follow-up raids on the Japanese carriers.  While the Enterprise is undamaged, much of its air arm has been destroyed.

 That’s kind of a fun scenario to play with, but how does it give us battleship versus battleship action?  Well, let’s say the US air raids leave one of the Japanese carriers damaged and unable to move fast.  The raids have also required high-speed maneuvering on the part of the carriers and their escorts.  High-speed maneuvering drinks fuel at five times the normal rate for a battleship and over ten times the normal rate for a destroyer.  The carriers can make it back to their refueling ships.  A considerable number of their escorts can’t by the time the air attacks are for the most part over.  The US sends 2 or 3 relatively undamaged battleships out, with the Enterprise’s remaining fighters providing air cover.  The Japanese move the two battleships accompanying the carriers between the US battleships and their wounded carrier.  And that sets up a battleship versus battleship match up.  The US would be likely to win because the Japanese Kongos had only about two-thirds the fire-power of most of the US battleships.

I suppose that with both sides having lost a lot of airpower we might even see a major fleet action between the Japanese battleship fleet and the US, possibly over Wake Island.  Not likely, but fun to play with.

The Germans choose bi-planes.  This has been mostly about battleships, so let’s add in at least one biplane scenario.  In the mid-to-late 1930s the choice between biplanes and monoplanes wasn’t all that clear cut.  Monoplanes were faster.  Biplanes were more maneuverable.  The results of the Spanish Civil War were ambiguous as to which quality was more important.  The Italians decides to squeeze in one more generation of their very maneuverable Fiat CR-series biplanes, though they also produced some monoplanes.  The Soviets produced both monoplanes and biplanes, and tried futilely to coordinate them to get the best of both worlds.  The British went mostly with monoplanes, though they did produce a fair number of Gloster Gladiator biplanes.  The Germans went exclusively with monoplanes and their ME109s made most of the planes in most of the opposing aircraft obsolete.  Let’s say they Germans put much of their energy into producing next generation biplanes roughly comparable to the Gladiator and the Italian CR-42.  Do we end up with biplanes playing a major role in the first part of World War II?  It’s a fun idea to play with, but unlike the Me109, a German fighter biplane wouldn’t obsolete opposing fighters.  Much of the reason Germany was able to bluff at Munich and win over Poland and France was that they went into mass-production of much superior fighter plane, and opposing airforces were scrambling to catch up.  We might still have a World War II, but it might be postponed or take a very different shape.

Alternate History: What If the Washington Naval Treaty Talks Failed?

What Actually Happened: After World War I, the US was in a position to quickly displace the British Royal Navy as the strongest naval power in the world.  The US had enough powerful modern battleships and battlecruisers in the :pipeline that by 1924 the US navy would surpass the British.  Given the lead time for building new capital ships, the British could not avoid being surpassed, even with a massive national effort.  The British would still have more capital ships, but most of them would be older and far less powerful than the ones in the US fleet.


In spite of that seemingly powerful position, the US had a problem.  In the aftermath of World War I, isolationism was growing and it was looking increasingly likely that many of those new ships would be scrapped rather than being completed.  The US basically bluffed on a weak hand.  Great Britain and Japan knew that the US could outbuild them if it chose to do so.  The US offered to give up its potentially dominating position in favor of parity with Britain and near-parity with Japan—a 5-5-3 ratio in capital ships.  That meant that the US would scrap most of the powerful new battleships and battle cruisers it was building.  In return, the British would scrap enough older ships to get to tonnage equality with the US.  The Japanese would scrap several ships they were building and agree to overall inferiority to the US and Britain in capital ships.  The US proposed a ‘battleship holiday”—essentially no more building of battleships for 10 years.  That didn’t quite happen, but it came close.  In addition the treaty limited the tonnage of battleships and aircraft carriers the powers could build.  It limited the size and armament of the cruisers the powers could build, so that cruisers didn’t become battleships in everything but name.  A treaty cruiser had 8 inch guns and theoretically weighed 10,000 tons.  Many of the naval powers cheated a little on the limits.  The Japanese cheated quite a bit, and ended up with more effective cruisers because of the cheating.


The Washington naval treaty shaped the US, British and Japanese fleets of the early part of World War II.  It finally broke up when the Japanese refused to renew it in the mid-1930s, but most of the ships of the early part of World War II were either allowed to remain in service due to the Washington naval treaty or were built within treaty limitations.


The treaty also forbade the US and Britain from building new fortifications and certain other types of facilities in the Far East.  That left the Philippines less fortified than the US wanted them to be, and left Guam essentially defenseless.


What might have happened:  Japan calls the US bluff.  They demand equality with the US and the British and walk out when they don’t get it, counting on the growing isolationism of the US to scupper US building plans.  With Japan not on board, the US is faced with Japanese naval plans to build 8 capital ships every three years.  If they do that and the British and US don’t respond, the Japanese will end up with a larger and more modern navy than either of their potential opponents within a fairly short time.  On the other hand, Britain is not financially able to keep up that kind of pace after the financial drain of World War I, and the US congress does not want to pay for the program that would give the US dominance.


Given the Japanese refusal to reach an agreement, the US stretches out, but does not scrap its building program.  US anti-Japanese sentiment is such that the US is not willing to allow the Japanese to build up a fleet that could dominate the Pacific.  US and British officials quietly agree not to build at a rate faster than is necessary to maintain a 5-5-3 ratio in relationship to the Japanese.


The Tokyo earthquake of September 1923 puts this incipient arms race on hold for a while.  The Amagi, one of the battlecruisers Japan was building, is destroyed beyond repair, and the widespread damage that killed over a 100,000 people from the earthquake and subsequent fires and Tsunamis and left over a million homeless also left the Japanese government with less resources to pursue an arms race.  Also, the US humanitarian response to the earthquake impresses the Japanese and temporarily defuses tensions between the two countries.  The Japanese quietly cut back on their buildup, though they don’t entirely stop it, partly due to interservice rivalries with the Japanese army.  Through the rest of the 1920s, the three major naval powers tacitly adhere to approximately the 5-5-3 ratio, though the Japanese don’t acknowledge that they have accepted that ratio.


Navies are somewhat larger and more expensive in the 1920s than they were historically, and the US maintains a somewhat larger army due to the perception of a potential Japanese threat.  In the booming 1920s, the stain of building and manning the extra battleships and battlecruisers is minimal for the US, but serious for the British.  However, the British are unwilling to give up their centuries-old naval dominance to the US or Japan, so they maintain a building program that they really can’t afford.


The British try to economize by upgrading older ships and keeping them in se4rvice longer, but the new US and Japanese battleships with 16 inch guns and sophisticated designs that incorporate the lesson of Jutland are much more powerful than pre-World War I British designs.  British capital ships are considerably old than US or Japanese equivalents, so the amount of building or rebuilding necessary to maintain parity is much larger for the British than it is for the US or Japan.  By 1929, the British ‘equivalence’ to the US has become an increasingly threadbare pretence, with numbers filled out by older, less powerful ships partially rebuilt but unable to really compete with US and Japanese ships.


The US tries again for a naval arms limitation treaty in 1927, but it falls apart because of British insistence on having enough cruisers to protect its long sea lanes, and Japanese reluctance to formally accept a position of inferiority.  The 1920s are an era of relative restraint on the part of the major naval powers, but no formal restrictions.


The emphasis in the 1920s remains battleships, though each of the three navies does build some aircraft carriers, and they do modernize their battleships to make them less vulnerable to aircraft.  As they did historically, Lexington and Saratoga become aircraft carriers rather than battlecruisers.  Both the British and the Japanese create similar conversions.


The US stock market crash that signaled the start of the Great Depression comes a little earlier than it did historically, but within a couple of months of the historic time.  However, it deepens more rapidly in Europe because the British are not able to hold back the cascade of bank failures in eastern and central Europe as long as it did historically.  In Europe the depression is even deeper than it was historically.


International trade falls apart in the face of protectionist pressures, just as it did historically.  The European powers and the US are hurt by that collapse, but they can be somewhat self-sufficient due to their control of large areas with most of the natural resources their economies require.  Cash-strapped governments are forced to cut back operations and maintenance on their oversized fleets, but while economies shrink, the  larger ones do have internal markets or colonies capable of sustaining them to some extent.


However, the Japanese find themselves locked out of global markets they have depended on, just as they were historically in the Great Depression.  They aren’t self-sufficient, and their small empire is not capable of sustaining even a smaller modern economy.  They react the same way they did historically: by an increased militancy aimed at carving their own empire out of China.


So where does this go from here?  Does it lead to a World War II approximately on schedule?  If so, how is that war different from the historic one?  Who wins?  Do we end up with more cool battleship versus battleship naval battles?   .

Book Review: The Pearl Harbor Myth By: George Victor

Yet another entry into the “Roosevelt provoked the Japs and knew about Pearl Harbor in advance” genre.  It differs from many of the earlier books in that genre in that it says that Roosevelt’s supposed actions were necessary and may well have saved the world from some very nasty times.

 Basically the theme of this book is that in the summer of 1941 FDR was afraid that the Japanese would jump into the war with the Soviet Union, pinning down Soviet troops and making a Soviet defeat inevitable.  As a result, he responded to the Japanese occupation of southern Indochina with a series of actions such as the oil embargo that made it inevitable that the Japanese would turn south against the western Allies rather than north against the Soviets.

 The book claims that FDR and people within his administration knew that those actions against Japan made a Japanese attack almost inevitable and had previously rejected them for that very reason.  Several high administration officials are quoted rejecting various elements of the sanctions against Japan before the German attack on the Soviet Union for just that reason.

 Again according to the book, FDR and company had decided by the summer of 1941 that it was necessary for the US to enter the war because in the long-term the Axis was a threat to US security and the Soviets and British could not successfully counter it on their own, even with US arms.  FDR took a two-track strategy to get the US actively in the war.  First, he escalated US involvement in the Atlantic to the point where the US was essentially waging an undeclared naval war against Germany—firing at German U-boats on sight over a major part of the Atlantic, convoying merchant ships most of the way to Britain, etc.  Second, he continued to both provoke Japan and offer tempting targets for it, while pursuing negotiations with Japan to hopefully postpone any war in the Pacific until the US was more prepared for it—hopefully until the spring of 1942.

 In the Pacific, FDR continued to keep the Pacific fleet at Pearl Harbor, in spite of the fact that the admiral initially in charge of the fleet felt that it was too vulnerable there and protested so strongly that he had to be replaced.  FDR and company also began building up US forces in the Philippines, but that buildup consisted primarily of offensive weapons like B17 heavy bombers rather than of defensive weapons.  Also the pace was fast enough to be provocative but too slow to actually offer much chance of actually defending the Philippines.

 According to the book, the preferred FDR strategy seemed to be getting into the war with Germany directly through provoking incidents in the Atlantic.  When that didn’t work, he upped the ante in the Pacific by hardening the US negotiating position.

 As to Pearl Harbor itself, the book offers no good direct evidence that Roosevelt knew about the attack in advance, but it does offer a lot of circumstantial evidence.  As to Roosevelt’s motive in not offering more specific warnings to the commanders in Pearl Harbor, the book claims that FDR was afraid that if the base was on alert the Japanese would abort the attack.  Roosevelt’s greatest fear was a Japanese attack on the British and Dutch in the Far East that didn’t include an attack on the US.  He had contingency plans to try to bring the US in anyway under those circumstances, but given the power of isolationism in the US, there would be no guarantee that the US would enter the war.

 So why didn’t the commanders on the ground at Pearl Harbor (Kimmel and Short) put their forces on a more alert posture given the warnings they did receive?  The book claims that the “War Alert” of late November 1941 tied local commanders’ hands by telling them that the message should be given only to senior level personnel and that nothing should be done to alarm civilians in the area.  It also tied their hands by not rescinding their standing orders, which gave priority to training.  The book claims that Short, the army commander at Oahu, was initially very concerned about an air raid, but that his superiors made it clear that sabotage was the primary fear and that they were or should have been aware that his disposition of forces was designed to protect against sabotage and not against an external attack.

 The book points out that at least one high Roosevelt administration official had prior to the attack stated that US policy was to maneuver the Japanese into firing the first shot while trying to avoid taking too much damage.  It claims that leaving the fleet at Pearl Harbor and not fully informing the local commanders was part of that policy.

 All of this sounds like an attack on FDR and his administration.  The author claims that it is not.  He says that Roosevelt may very well have kept the Japanese from attacking the Soviet Union at its most vulnerable time in late summer of 1941.  He also says that US entry into the war was necessary to defeat the Axis, and that a major Japanese attack on US forces was the only way that would happen given US isolationism.  He says that FDR could have had no idea how devastating the Japanese attack at Pearl Harbor was going to be, and in any case drastically underestimated Japanese military capability.  He also says that much of the destruction at Pearl Harbor was actually due to a fluke—a bomb going just the wrong place in the Arizona and causing far more US casualties than would have occurred under normal circumstances.

 So, how much of this do I believe?  I do believe that the US oil embargo against Japan foreclosed the Japanese option of going against the Soviet Union.  It did so at a time when the Japanese were still debating that option.

 A lot of people have claimed that the Japanese were unwilling to attack the Soviet Union because of the Soviet performance against the Japanese at Nomanham.  I thought that for a long time, but I no loner do.  Nomanham seems to have had more to do with internal Japanese military politics than with relative Japanese/Soviet power or fighting ability in the area.  The Japanese sent one green division into the fight, joined at separate times by tank elements, heavy artillery elements, and part of another division.  The Japanese made it clear that they were not going to escalate the battle to include other areas of the Manchurian frontier, thus allowing the Soviets to put a far larger portion of their local military power into the battle than the Japanese did.

 Even given the almost inevitable Japanese defeat at Nomanham, local commanders were willing and even eager to go another round with the Soviets, and were in process of building up forces to do so when their superiors stepped in and stopped them.  I may be wrong on this, but I suspect that the Japanese army took advantage of the defeat to clip the wings of militaristic local commanders who had already gotten the Japanese into a war with China by their independent actions, and seemed likely to get them into another one with the Soviets.  Many of the people in the chain of command at Nomanham were purged or reassigned, which helped bring the local military under central control but also cost the Japanese most of the potential value of lessons learned in the fighting against the Soviets.

 I’m guessing that the Japanese would have headed south even without US prodding, but that’s not a given.  They had not made a decision to do so before the embargo.

 Did Roosevelt intend to divert the Japanese south away from the Soviet Union?  In hindsight it would have been logical for him to have done so.  If he did, he showed a lot of foresight.  I’m not entirely convinced that he did so deliberately.

 Did Roosevelt want to enter the war?  Sure.  Did he know that war with Japan was almost inevitable by late November 1941?  Again, sure.  Did the commanders at Pearl Harbor know everything relevant to their positions that FDR and his administration knew?  No.  Did they know enough to know that they needed to be on the alert?  Sure.

 Did Roosevelt know that a Japanese air raid on Pearl Harbor at the beginning of the war was a significant possibility?  Sure.  That was a Japanese option that had been war-gamed many times and had been warned against multiple times.  Roosevelt had to have known that the fleet was vulnerable there.

 Did Roosevelt know specifically and certainly that the Japanese were going to attack Pearl Harbor early enough to warn the local commanders?  I doubt it, but I wouldn’t be horribly surprised to be wrong.  Let’s say he did have specific knowledge of the coming attack and a general idea of the timing.  What could he have done differently that would have led to a better outcome?  Send the fleet to sea?  A bunch of old battleships and at best two carriers against 6 Japanese carriers?  Likely outcome: The fleet still loses a good many capital ships and it loses them in deep water with heavier casualties and no salvage options.  Keeping the fleet within air range of Pearl Harbor would help some, but probably not enough to avoid a US defeat.  Even if the US won that battle it would leave a murky situation.  Who really started the fighting?  Was it FDR playing games like he was doing in the Atlantic?  Having the fleet clash with the Japanese at sea would not leave the country united like having it attacked in harbor did.

 Bring the fleet back to the US west coast?  That signals that the Japanese have a free hand in the Far East and might have led to a Japanese attack only on the British and Dutch.  Put Pearl Harbor on maximum alert, with everyone at war stations?  Might help, but it also might lead to the Japanese detecting the alert and deciding not to attack.  If the Japanese do attack and the US fleet cleans their clock then do the Germans still declare war?  Quite possibly no, which means that the US ends up fighting Japan while the Germans have far less to worry about on the western front.  Britain almost certainly could not have opened a second front without US help.  The Soviets almost certainly could not have finished the Germans off without a second front, and even if they did it would lead to Soviet control of most of Europe.

 This isn’t to say that Roosevelt didn’t make serious mistakes.  He did.  He should never have put the Pacific fleet at Pearl Harbor to begin with.  It was too vulnerable there and he knew it.  Once it had been there for a while and tensions with the Japanese started heating up withdrawing it would have sent the wrong signal, but he was foolish to put it there in the first place.  He was also foolish to put so many B17s in the Philippines. There he probably bought in to the arguments of air power advocates that level bombers were potent weapons against warships.  That wasn’t true, at least not early in the war.  B17s were virtually useless against ships in the early part of the war because they weren’t accurate enough, though with better techniques they did become useful later in the war.  Dive bombers and aerial torpedoes were effective against ships early in the war.  Level bombers weren’t.  Putting the B17s in the Philippines was a waste of good planes and good pilots, though it did make the Japanese less likely to bypass the Philippines and go against the Dutch and British only.

 Roosevelt certainly didn’t realize how devastating a Japanese attack on Pearl Harbor could be.  Almost nobody else in the US military did either.  The Japanese pilots at the beginning of the war were probably the best in the world in terms of bombing accuracy.  Roosevelt couldn’t have known about Japanese innovations like the bombs converted from naval shells that made the attack much more deadly than it would otherwise have been.

 So, would I recommend the book?  Maybe, but with a read with caution warning.  If you read it, you might also want to read something stating the case for the other side too.