MH-18: Victory in the Pacific

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MH-18: Pacific Victory - Strategic Overview Naval & Amphibious War – Operational Level

• US Grand Strategy: still Germany “first” => but…– political reality could not be ignored:

• Japan bombed US first at Pearl Harbor• American Public demanded revenge on Japan

• Result => Grand Strategic objectives & priorities adjusted:– Pacific theater gets higher political & military priority

• Also: setting strategic priorities forced leadership:– Allocate scarce resources among competing CINCs

• (i.e. forces, logistics and supplies)• Not => best strategic objective or COA to pursue (CINC personalities)

• Result: logistics and political considerations drive=>– Allied Strategy => producing ad hoc strategic approach =>– “Dueling” operational strategies in Central & SW Pacific

• US called them “complementing strategies;” Brits called them competing

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Strategic Opportunity vs. Limited Resources

• Following Battle of Midway (June 1942)=> – CINCPAC (Nimitz) still left with only limited resources– A Major limitation for prosecuting war in Pacific theater– Only able to assign 1 UMSC division to secure Guadalcanal– PACFLT ships barely able to protect Australian LOCs

• Later US mobilization expanded MPN & logistics=>– Made sufficient forces available to Pacific (by latter half of war)– Enabled US to pursue & adequately support:

• 2 separate pronged strategies led by MacArthur (SW) & Nimitz (Central)

• As Pacific War was fought => – Number of ships sunk surpassed all previous conflicts– Combined Air/Sea/Land ops accelerated toward the War’s end

• But what would finally put an end to the war with Japan?

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South Pacific (August’42-December’43) Guadalcanal

• Navy & USMC conducted operations in South Pacific =>– Specifically in the Solomon Islands

=> at Guadalcanal

• USMC continued to defend against escalating assaults– Japanese conducted wave upon wave

of frontal assaults

– Suffered horrendous casualties in process

– 15K killed or missing – 9K from disease - 1000 captured

• Meanwhile=> Naval battles also fought throughout– Conducted in & around Solomon

Islands (Salvo Island- USN defeated)

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Operation Cartwheel

• Series of battles then conducted in parallel in SW Pacific

• Background:– Casablanca Conference of Jan 1943– Key issue: unity of command in

Pacific Theater:– Army (MacArthur) versus– Navy (Nimitz)

• Question: who’s in charge & whose strategy will prevail:– (i.e. Given priority for resources &

manpower)

• Macarthur’s proposed strategy?– Capture ?______________ in 1943 – CJCS response?– Too ?__________ & ?__________

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Fallback Strategy • CJCS Compromise:

– 2 pronged drive converging on Rabaul

– Tactical objective: capture or isolate Rabaul

• Concept of Operations (Map):– “Bull” Halsey to advance up

Solomons to Bougainville

– MacArthur advance along New Guinea east coast

• Attack New Britain

• Then isolate Rabaul

• Significance?– PACFLT employed to meet

political objectives (PH revenge)

– Cartwheel also would become model for entire Pacific campaign

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Air Power’s Role in SW Pacific

• Key role in Cartwheel & future Leap-frog strategy– Employ CAS for invasion=> troops establish runways=>

– Used as FOB & Air Field to attack next island target

– Then US starts the cycle over again for next “Island leap”

• MacArthur’s top air commander & strategist – MG George C. Kenney

– Developed new & innovative tactics

– What kind of innovative tactics?

• Employed land based air to strike Navy & defenses– Modified B-25s w/8 50 cal MGs in nose

– B-25s fly low level sorties against ships• Skip 100# bombs into enemy shipping

• Big improvement over past USAAF ops against Japanese ships

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Japanese Response – April 1943• Japanese successfully deploy 8th , 17th, & 18th Armies

to SW area of operations from China & Japan– Then re-deploy 51st division from Rabaul to New Guinea– Magic forewarns allies of Japanese intent:

• Battle of Bismarck Sea – MG Kenny’s modified B-25s make low level & B-17s make high level attacks– Land based Air destroys Japanese troop transports for decisive Allied victory

• Impact: loss of this huge armada, loaded with supplies and troops, ended Japanese hopes of retaining control of New Guinea

• Also gains US Navy’s reluctant recognition of new Air Force (AF) tactic

• Magic also alerts allies of Admiral Yamamoto’s planned air trip:– Action taken by allies?

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Amphibious Campaign- Island hopping • Macarthur & Halsey continue duel

advance:– Conduct amphibious landings or

isolate enemy at:• New Georgia, Bougainville, New

Britain, etc.

• Tactical & Operational objectives & strategy:– Capture Japanese built air fields (or

build them on captured Island)– Occupy & stage for further advance up

island chain– Skip & isolate heavily defended island

defenses:– Close off enemy’s LOC instead

(Illustrated by Kolombangara)

• Capture more air strips & “island hop” all the way to Japan

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SW Pacific “Island Hopping:” Results & Significance:

• Each seized island provided air/logistic base for next hop• Isolated Japanese units died on vine =>

– Therefore it presented no more operational threat

• Useful precedence established:– Successful operational strategy was used throughout rest of war

for entire Pacific Theater

• Allied buildup in Pacific & air/sea control enhanced– Success encouraged more support & higher priority

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Central Pacific Campaign (Nov’43-Feb’44) Strategic Aims for Pacific

• Trident Conference (Washington DC- May’43)– FDR, Churchill, & CJCS establish strategic aims for Pacific

Theater

• Strategic aims included:– 1. Cut off Japanese raw materials

– 2. Conduct strategic bombing on Japan

– 3. Invade Japan home islands & destroy military power

• Operational Strategy:– Build on success in Burma, So. Pacific, China=>

– Then launch strike against Japan itself

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Concept of Operations: Two Opposing Concepts• 1. Drive across central Pacific

– (who’s proposal?):– Use Coral Atolls for launch sites (logistics,

FOB staging, etc)

• 2. Continue drive in So Pacific via New Guinea & PI (who?)– (“I shall return”)– But he needs Naval support in

order to accomplish this concept– South Pacific Strategy- Halsey’s role

(“MacArthur’s Admiral”)

• CJCS compromise?– Balance two strategies –

• Complimentary?

– ADM King’s proposal modified– how? • Strategies converged where? _______________• To provide Sealift for MacArthur’s “return”

ADM King

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Navy’s Key Role- Sea Power PACFLT Order of Battle

• US shipbuilding on step by Summer’43:

• Major positive impact on US Order of Battle– Essex class Fleet Carrier (CV):

27K tons & 100 A/C

– Independence class light Carrier: 11K tons & 50 A/C

– CV aircraft: F6F Hellcat

• Commander 5th Fleet (Spruance) forces comprised:– 6 Flt CVs, 5 lite CVs, 12 BBs,

9 heavy & 5 lite CRs +

– 56 DDs & required support: Oil, Ammo, Supply ships

– Submarines had a special role*

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Submarine Campaign- Pacific • Most effective offense throughout Pacific:

– Submarine (SS) attack on Japanese commerce

• Slow start at beginning due to number of reasons– Lack of leadership & tactical skill (peacetime COs)

– Faulty torpedoes & denial of problem at BUWEPS

– Resulting in self destruction of USS Tang

• Once solved => – Japanese Navy & merchants very vulnerable:

– Japanese conducted no serious prep against SS threat• Prior to & during early part of War

– No adequate staff or command level attention devoted

– No convoy system developed or anti-SS resources

– When problem finally recognized => too late

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“Sustained Combat Operations at Sea”• PACFLT dominated seas in & around Japan by Fall’43

– USN Capacity & capability unsurpassed

– Logistics, re-supply, & repair at sea unmatched

– 5th & 3rd Fleet HQ staffs simply rotated

– The Fleet itself was always at sea• HQ ashore planned for upcoming operations

– Japan simply could not compete at this level

• Fleet able to conduct opposed amphibious landings– Protect landing forces with air & sea power

• Fleet also able to conduct major surface battles (CV air)– All the while remaining at sea indefinitely

– Many sailors stayed at sea almost entire war

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Central Pacific Strategy• The drive through the Central Pacific given higher priority

– Especially by the Navy leadership & many members of CJCS

– SW Pacific drive seen by many as based more on “political” considerations than strategic or operational priorities

• (FDR wanted to keep MacArthur as far away from Washington as possible)

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Tarawa (Nov’43)- Objectives • Tactical & Operational

Objectives:– Gilbert Islands were 1st

objective of Central Pacific Drive strategy

– Target: Betio in Tarawa atoll

• Battlefield preparation:– Inadequate NGF support

– Poor recon (Photo from air)

– Lack of critical Hydrographic Reconnaissance data

– Reef ½ mile out from landing beach would block landing craft

– Marines must wade ashore

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Tarawa: Execution • Lack of sufficient gunfire support & preparation = high casualties

– Lack of proper coordination between landing force & sea commanders– USMC landing force come ashore to kill zone wading in head+ high water– Planners grossly underestimated enemy strength & defense

• 5000 Japanese troops dug in with heavy weapons- pour it on Marines

• Serious lack of adequate information about beach landing site:– Coral reefs ground landing craft far off shore– 2nd USMC forced to wade ashore – many drown w/heavy equipment & ammo

• 5000 finally make it ashore through heavy fire, but 1500 are dead or wounded

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Tarawa: Results

• Bitter lessons learned – Casualties: USMC: 3381 (990 KIAs) out of 18,600– 4 Medal of Honors (MOH) awarded

• (3 post humorously)

– Japanese: 17 survivors out 5000 man garrison

• PACFLT concluded better & more up close hydrographic recons required prior to future amphibious landings– Underwater Demolition Teams (UDT) reason for being:

• Reconnaissance & demolition

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Central Pacific Drive Continued• USN next month op was success:

– Isolation of Truk (750 due west) – Precludes Truk’s use by Japanese

Air Craft– Unable to stop US invasion of

Eniwetok - Feb 44: – Luck: early US attack prevented

Eniwetok adequate defense– Result: USMC lives saved due to

earlier Feb assault • Eniwetok’s capture => Operational

impact: – US now 1000 miles west of Tarawa:

• Closer to next operational objective: Mariana atolls – Also 1000 miles closer to US strategic

Objective: (what?)– ?________- US to use Marianas as

air base to bomb ?_________________

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SW Pacific Operations Linked to Central Pacific• Two separate Pacific Drives continued

– Mac isolated Rabaul & then seized Hollandia

• Wakde & Biak soon taken after Hollandia– Wakde & Biak’s Operational significance?

– Within range of PI with American Aircraft

– Japanese also realize the significance of threat

• Impact of friction & good timing:– Macarthur’s luck holds at Biak– Spruance (5Flt) attacks Marianas

• Japanese immediately cancelled attack on Biak Island (never to return)– Prepare to deploy Task Force to Central Pacific

• Spruance’s attack in Central Pacific sets in motion new Japanese Operation: “A-GO”

• Tactical Objective: – Decisive Battle in Central Pacific to destroy PACFLT’s 5th Fleet

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Central Pacific => The MarianasSaipan, Tinian & Guam

• Saipan - closest major Island in the Marianas:– USMC 2nd & 4th divisions

tasked to take Saipan – Army 27th ID in support– Also tasked to take Tinian

following Saipan

• Saipan was defended by 32K Japanese– (but its defense preparations

were incomplete & soon fell)– Op. & Strategic significance? – Saipan is now within B-29 range

• US secured Tinian & Guam by July & early Aug after hard fighting

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Battle of PI Sea • Spruance’s advance on Marianas & attack on Saipan has major

impact on Japanese strategy – Forces Japan to dump Biak & establish 1st Mobile Flt:

– 1st Mobile Flt comprises:

– 9 CVs w/400 AC, 5 BB, 13 CR, 28 DDs

• All units re-deployed to Central Pacific

• Tactical & Operational Objective:– Destroy American 5th Fleet

• Spruance kept Fleet between Saipan amphibious ops & Japan’s Fleet– Japan forced to attack=> 4 waves of 373 AC strike (only 100 penetrate CAP)– TF58 A/C sink one CV & damage 3 others (US SS also sink 2 CVs)

• Result: Although bulk of Japanese Fleet escapes:– Battle has big Operational impact on Japan-what? – Major loss of ?_________ __________ ________ _______________

• USN Fleet structure/coordination & power projection validated

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Philippine Invasion • King & MacArthur disagree

over final operational strategy of Pacific war– King wants to continue island

hop to Mindanao • (in Southern Philippines)

– Then to make big jump to Formosa & China Coast (Map)

– This is here “scouts & raiders” have reconned potential beach landing sites in China

• Future FOBs for Japan’s invasion

• MacArthur continues to press for liberation of PI people

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Leyte Gulf -Oct 44- July 45

• Convergence to 2 prong drives=> both toward ?___________________– Key stepping stone to Luzon (main PI island)

• Key events: Halsey conducts engagements off to east of PI – Destroyed much of Japanese land and CV based aircraft

• Forced Japanese to return to Japan for repairs & replace pilots

– Halsey deduced that Japan lacked strong force in PI (wrong)

• Japanese prepared for decisive battle with complex plan:– 4 separate TF to attack US force in waters off PI

– CVs from Japan to draw US CVs away from Luzon

– Surface Flt (BBs) to move through San Bernadino Strait:• Tactical objective: attack US landing forces landing at Luzon

– Remaining Japanese TF to move thru Surigao Straits

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Leyte Gulf: Execution • Oct 20: MacArthur attacks NE

coast of Leyte with LTG Krueger’s 6th Army– Encounters moderate resistance

but 6th Army fights inland

• Japanese respond but are spotted by US submarine– US Navy attacks & sinks

2 heavy Japanese cruisers:– This rattles Adm Kurita, Commander

of main San Bernadino Task Force

• Japanese A/C from Leyte attack Halsey (Princeton is badlyt hit)– But Halsey’s A/C find Kurita’s TF &

attacks:– Sink super BB Musashi – Kurita becomes even more rattled &

retreats from PI

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Halsey’s Blunder• Halsey sails entire Fleet North

in search of more targets

– Leaves nothing behind to defend Amphibious ships!

• Meanwhile Imperial HQ ordered Kurita to return to fight:– Kurita now unopposed

for transit of San Bernie Strait

– Only few DDs & escort CVs between him & what?

• ?_______ ________ _______!

– But still able to harass enemy & prompt Kurita’s withdrawal

– Very close to disaster for Americans (& Halsey’s reputation)

• By Christmas last Leyte port taken* by 6th Army- mop up ops follow

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Ominous New Tactic Revealed

• Ominous new tactic makes its debut at Leyte Gulf: – A serious new threat used against US in future battles

– What is the new tactic used by Japan near end of war as a last resort?

– ?_____________ ____________

• Japan strips all available forces to reinforce Leyte– Taken from Luzon & Okinawa

– Major future impact later

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Luzon -Jan 45 • MacArthur finally fulfills his

promise to return– Navy pays dearly price in process => why?

• ?_________________ attacks on USN• Meanwhile General Yamashita

abandons cities for mountain defense• 6 Jan: 6th army lands on Lingayen Gulf:

– 4 infantry divisions => total of 175K men– 6th Army marches 40 mile in 2 weeks thru

light resistance• 29 Jan US makes 2 more landings:

– NW & SW of Manila • Though Yamashita ordered cities

abandon =>– Japanese Marines fight on to keep Manila

• (Not in his Chain of Command)– Manila virtually destroyed as result - 100K

civilians die & Yamashita is blamed for it• And subsequently tried and executed for it

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Final Campaigns- Iwo Jima (Feb-Jun’45) • Background:

– Operational significance of Iwo: Japan’s early warning– Also Japanese fighters based on Iwo harass B-29s– B-29s conducting bombing raids from Marianas

• Suffer heavy losses without much to show for it

– Also emergency landing field badly needed upon return flights

• Order of Battle:– Japan: LTG Tadamichi commands 21K with 1000 guns

• Strong defensive positions: dug in deep in caves and tunnels

– US: VADM Turner commands Joint Expedition force• LTG Holland Smith commands Troops: USMC V corps• Comprised of: 3rd, 4th, & 5th Marine divisions• Armored amphibian tractors & Navy NFS

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Iwo Jima- Plans & Objectives

• Strategic, Operational, tactical Objectives:– Japan: defend Iwo & prevent its capture

– US: capture Iwo & use for B-29 emergency landings

• Concept of Operations:– Japan: defend fm complex system of caves &

tunnels

– US: attack abreast on SW beach=> main effort to south

• Iwo Battlefield preparation:– Japan: withdraw to mountain areas & await

attack

– US: Recon beach landing areas & NGF prep

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Iwo Jima-Execution• 0935 19 Feb: 1st wave of

armored tractors insert– 5th Div on left & 4th Div

on the right (Map)

• On left 28th infantry regiment turns South to Suribachi– Gains crest after 4 days of heavy

fighting (plants American flag)

• Main effort to North – slow advance of 5th & 4th Divs– Japanese conduct fierce resistance

all along (red) defense lines from tunnel/ & cave network

– Island finally secured after heavy fighting on 26 March 1945

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Iwo Jima- Results• USMC:

– 5931 KIA/17372 WIA out of 71245 put ashore

– (27 MOHs awarded – half post-humorously)

• Japan: almost all defenders killed– 216 POW survivors taken (Korean civilian contractors)

• US eliminated fighter threat to B-29 raids on Japan• Emergency landing field secured

– 2251 heavy bombers (B-29s) & crews saved from ditching

– 24761 total made emergency landings on Iwo Jims airfields

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Okinawa (April – Jun 1945) • Background:

– Final land battle of the Pacific war

– Capture would provide a staging base for air strikes and invasion

• Order of Battle:– Japan: LTG Ushijima commands

32nd Army (77K)• Plus 23K Navy and Oki conscripts =

total: 100K

– US: ADM Nimitz overall Theater commander- ADM Spruance, CMDR 5th Fleet w/1200 ships

• LTC Buckner: 10th Army (III & XXIV corps) 182K

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Okinawa: Plans & Objectives• Strategic, Operational, tactical

Objectives:– Japan: prevent capture of Oki as

long as possible:• Inflict maximum casualties on

assaulters

– US: Capture Oki & use it as base to stage invasion of Japan

• Concept of Operations:– Japan: defense in depth with main

strength to South:• 3 major defense lines following E-W

ridge lines

– US: Land III & XXIV Corps & attack defense lines to North & South

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Execution – Easter Sunday-1945

• US: After heavy NGS bombardment, land 2 corps (2 div each) on west side– III corps proceeds to left & XXIV to right

• Marines turn North & Army south into 1st defense line– Ushijima delays counterattack until 12 April:

– Awaited massive air-sea attacks on 5th Fleet

– Counterattack easily absorbed by XXIV

• Meanwhile III corps overran most of central & North Okinawa– Buckner shifts portions of III Corps to

southern engagement

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Final Assault & Results• 18 June Buckner launches final assault on 3rd line:

– Buckner is killed by Japanese shell– III corps commander takes over

• Declares Oki secure on 21 June 1945

• Throughout numerous Kamikaze attacks conducted on the Fleet– Launched in 10 major waves severely damage fleet– Last wave launched on 22 June

• Results:– Okinawa secured for base of operations

for Allied invasion of Japan– Casualties:

• 10th Army: 7613 KIA/31800 WIA• Kamikazes sink 30 ships/damage

365 + 5K KIA• Japanese: 142K+

– (including Oki civilians)

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Japan Under Siege• Following establishment

of base at Okinawa, Japan constantly under attack from air and sea – Duration: June-August 1945

• The greatest direct impact came from land and sea based air

• Curtis LeMay => introduces new Air Force tactic => – From precision bombing to

incendiary area bombing– Conducts low altitude night

attacks (like RAF)

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Strategic Bombing• Strategic air campaign intensifies

from Oct 1944 to Aug 1945 – Tokyo fire storm kills 83K civilians;

• Japan prepares to resist to end:– Prepares up to 5K Kamikaze planes

& pilots (300-400 launched/hour)– Also suicide speed boats with high

explosives

• US planned amphibious landing at Kyushu– Estimated casualties for invasion

force => 700K!

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Manhattan Project• Meantime Manhattan project

successful– Proves feasible by summer of 1945

• VP Truman succeeds FDR upon his death=> – Then informed for first time

of Atomic Bomb weapon

• Truman decides to use it on Japan: – On 6Aub45=> B-29 drops first

Atomic Bomb over Hiroshima

• 90K people die in huge blast

– 3 days later => same thing over Nagasaki

• The atomic genie is now out of the bottle!

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Japan Surrenders

• Japan’s response to Atom Bomb:– Japanese cabinet argued no such weapon exists until

Nagasaki– Remained deadlocked over surrender– Emperor steps in and orders Japan’s surrender– Conditioned on his remaining in ceremonial position

• Japan surrenders (Sept 2,1945):– Japan’s delegation sign surrender instrument:– Signed aboard USS Missouri (MacArthur presiding)

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World War II- Assessment

• WW2 most destructive war in human history:– Cold War begins with A-Bomb always in shadows

• War finally ended Hitler’s threat of world domination– Along w/Mussolini & Japan’s Imp Gov

• From a tactical & operational perspective:– WW2 restored tactical & Op mobility to Battlefield

• Tanks, A/C, ABN units integrated & employed for land warfare

• Carrier Air for war at sea

– Amphibious operations for power projection:• Island Hopping strategy in SW & Central Pacific

• Amphibious Ops at great distances in Central pacific

– Logistics/supply system allowed nonstop deployed Fleet

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Assessment-2• New technology & weapon enhancements:

– Radar/Sonar & submarine warfare proved effective:• Enhanced Interdiction & protection of SLOC

– Improved C3I & better operational control & coordination• Superior allied Intel collection & analysis (Ultra &

Magic):– Deception & perception management– All gave distinct advantage to allies

• Superior command, control, & communications:– effective integration/coordination of all air/sea/land =>

• directed forces together toward common op. purpose

• Superior mobilization of industrial might:– all above supported by unmatched Log system & MPN– War economy & industrial capacity & vast available MPN– All effectively directed toward national objectives

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Assessment-3• WW2 continued WW1’s tactical develop & op concepts:

– Evolutionary process of improvement & refinement for:• Blitzkrieg w/tanks;• strategic bombing;• submarine warfare;• Amphibious doctrine (w L/L)

• In contrast to WWI:– Destruction was much greater scale (civilian & property)– Holocaust & Nazi atrocities shocking– Strategic bombing killed 100ks- cities/civilian population– Atomic bomb => Nuclear weapons => MAD Cold War strategy of 20th cent.

• Post WWII Cold War would make world bipolar– West versus East Europe divided world following WWII– NATO versus Warsaw Pact– Democracy & capitalism vs. Soviet dominated Communism

• War also ended or soon ended Western Empires– NTL: relative peace (i.e. no world wars) to present

• Although certainly “a hard and bitter peace” followed- JFK

Backup Slides

(The Details)

45

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• British question efficiency of Two Drive Strategy- (why?)

• US response? – Both drives mutually supporting?

– Real reason?

– (Macarthur vs King & Nimitz)

• Brits response: mutually competing (scarce resources)

• Macarthur’s advance in South West Pacific- (Map):– Op Objective: Philippines (leap

frog over hard points)

– Establish air strips for fighter escorted bombers =>

– Protect & further advance west

Two separate Pacific Drives- continue (1943-44)

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Papua

• Order of Battle:– Australian 7th & US 32nd

Divisions

– Japan: 11K on New Guinea

• Macarthur’s operational objective & strategy:– Defend & protect Australia

& its LOCs

– Control New Guinea

– Deny secure Japanese basing in SW Pacific

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Papua Execution:• MacArthur deployed US & Australian forces to Port Moresby

– Then attacked Buna (where allies get bogged down)

• MacArthur becomes impatient with lack of progress – Sends LTG Eichelberger to fix hold up

– He swiftly improves supply lines & combat power

– Improves food & morale

– Brings in tanks to support infantry

49

Papua Results• All operational objectives gained =>

– US regains operational initiative:– Japanese driven from Port Moresby & US holds Guadalcanal

• Buna captured within a month– Sanananda taken a month after– Several hard lessons learned WRT reducing Japanese defenses– US Casualties: 8500

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SW Pacific Drive- Objectives• Two separate Pacific Drives-

continued (1943-44) – In SW Theater Mac’s Op Objective: PI– Mac’s immediate objective: isolate

Rabaul & accelerate his advance– 1st Calvary Det (1000 troops) assault

Admiralty islands- specifically=> Los Negroes:

• (High risk op- barely in range of CAS)

– Mac is lucky: defenders concentrated where? • East end-=> Allows US attackers

time for re-enforcements =>• Beat off Japan’s counter-attacks-

• Hollandia (New Guinea)– The next target: – Tactical & operational objectives: – Isolate 40K more Japanese troops – Secure 3 Japan built air strips for

further advances

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Biak Island

• Biak soon taken after Wakde (325 mi west of Hollandia):– Wakde & Biak’s Operational significance?

– Within range of PI with American Aircraft

• Japan also recognized their Operational significance:– Prepare to attack Biak w/large Amphib & Naval force

– Operational objective: preclude US air strikes on PI

• Japanese strike force hastily withdrawn prior to attack:– False reports of large US Naval force prompts pull out

• Japan soon assembles even larger assault force:– Prepares to attack Biak once again:

– Fortunately for Macarthur, what changes Japan’s mind?

• Why do they cancel attack & deploy to Central Pacific?

52

Submarine Campaign- Pacific • Most effective offense throughout Pacific:

– Submarine (SS) attack on Japanese commerce

• Slow start at beginning due to number of reasons– Lack of leadership & tactical skill (peacetime COs)

– Faulty torpedoes & denial of problem at BUWEPS

– Self destruction of USS Tang

• Once solved => Japanese Navy & merchants very vulnerable:– Japanese conducted no serious prep against SS threat

• Prior to & during early part of War

– No adequate staff or command level attention devoted

– No convoy system developed or anti-SS resources

– When problem finally recognized => too late

53

Measure of Effectiveness

• MOE: total Japanese Naval tonnage sunk: 577K– 1113 Merchants & 201 warships

• (to include: BBs & CVs)

– SUBPAC losses: 52 subs (22% of force)

• Strategic Impact:– Major impact on Japanese war

economy – why?

– Interdicted vital raw materials (oil & steel)

– Key reason why Japanese started the war in first place

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The Marshalls: Kwajalein (Dec’43)

• Following Tarawa => Marshall Island group next:– TF58 (Mitscher) & Adm Turner

(COMPHIB) invade• Six CVs, 6 light CRs, 3 BBs plus

SS screen & amphibs

– Target: Kwajalein Atoll (Map)

– 8000 Japanese defended (but mostly admin personnel)

• US invasion success – (Thanks to Tarawa’s L/L)

– Several improvements in combat hydro recon made (UDT)

– Extensive NGF support prep

– Improved C3 & coordination between USMC & Navy

55

Hollandia’s execution

• MG Eichelberger achieves tactical surprise w/2 infantry divisions – Japan responds by landing 18th

Army:• Inflict 9K US casualties

– CV air attack Japanese ships

– But within month => Japanese demoralized troops withdraw

– US now has 3 more airstrips to support its advance

• Wakde & its airstrip successfully taken late May:– Wakde 150 mile west off New

Guinea- (see Map)

56

Saipan’s Execution

• Nimitz insists that 5th Flt attacks Saipan before Japan’s defense completed

• LTG Smith USMC attack w/2nd, 4th & 27th Inf. 20K complies– Sharp bitter fighting ensues &

Japanese resist

– Japanese eventually pushed to north side of Island

– Then Japanese launch largest Banzai attack of war

• Results: US 14K casualties– Japan: 32K KIA w/few survivors

– Civilians also killed by own troops or commit suicide

57

Guam & Tinian

• Guam & Tinian also were slated to be taken:– USMC 3rd & Army 77th

Infantry to attack Guam– USMC 2nd & 4th & Army 27th

Infantry divisions• Tasked to take Tinian following

Saipan

• US secures Tinian & Guam by late July & early Aug after hard fighting – By late Fall => B-29s able to

launch strikes on Japan

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Battle of PI Sea

• Spruance’s advance on Marianas & attack on Saipan has major impact on Japanese strategy – Forces Japan to dump Biak & establish 1st Mobile Flt:

– 1st Mobile Flt comprises:

– 9 CVs w/400 AC, 5 BB, 13 CR, 28 DDs • All units re-deployed to Central Pacific

• Tactical & Operational Objective:– Conduct decisive battle & destroy American 5th Fleet

• Japanese have a small tactical advantage over US?– Japanese tactical advantage? (Zero vs. Hellcat)

– Zero longer range (but no armor/self seal=> vulnerable)

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Battle of Philippine Sea - Execution• Spruance kept Fleet between Saipan

amphibious ops & Japan’s Fleet– Japan forced to attack=> – 4 waves of 373 AC strike– Less than 100 A/C penetrate Hellcats CAP – Survivors fly into heavy AAA from new BBs– Radar used to vector Hellcats to intercepts

• TF58 alerted by recon A/C to location of Japanese CVs:– VADM Mitshner launches his attack at edge

of his aircrafts’ range– TF58 A/C sink one CV & damage 3 others– US submarines also sink 2 Japanese CVs

• Result: Bulk of Japanese Fleet escapes:– But battle has big Operational impact on

Japan-what? – Major loss of Japan’s CV combat pilots

• Fleet structure/coordination & power projection validated

60

Leyte Island Assault Continues• LTG Krueger moves 6th Army slowly

twd Ormoc on west coast of Leyte– Japan strengthen defenses along mountain

range (N&S thru Island’s center)– 77th Div land south of Ormoc port

• Captured it 3 days later

• Japanese continued resistance w/ground & ABN attacks: – Combined attacks made to seize

airfield at Burauen– But soon resistance ceased soon

after Ormoc’s capture:• (Main port for Japanese

reinforcements & supply)

• Result:– By Christmas last Leyte port

taken- mop up ops follow– Leyte => High cost to Japanese:

most of 5 divisions lost – Navy & air casualties will

also impact remaining forces on PI