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MH-18: Victory in the Pacific. 2 MH-18: Pacific Victory - Strategic Overview Naval & Amphibious War – Operational Level US Grand Strategy: still Germany.

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Presentation on theme: "MH-18: Victory in the Pacific. 2 MH-18: Pacific Victory - Strategic Overview Naval & Amphibious War – Operational Level US Grand Strategy: still Germany."— Presentation transcript:

1 MH-18: Victory in the Pacific

2 2 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

3 3 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?

4 4 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)

5 5 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 ?__________ & ?__________

6 6 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

7 7 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

8 8 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?

9 9 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

10 10 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

11 11 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

12 12 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

13 13 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*

14 14 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

15 15 “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

16 16 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)

17 17 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

18 18 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 –2 nd 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

19 19 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

20 20 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 ?_________________

21 21 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

22 22 Central Pacific => The Marianas Saipan, Tinian & Guam Saipan - closest major Island in the Marianas: –USMC 2nd & 4 th 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

23 23 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

24 24 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

25 25 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

26 26 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

27 27 Halsey’s Blunder Halsey s ails 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 6 th Army- mop up ops follow

28 28 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

29 29 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

30 30 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

31 31 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

32 32 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

33 33 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

34 34 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

35 35 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

36 36 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 1 st 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

37 37 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)

38 38 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)

39 39 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!

40 40 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!

41 41 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)

42 42 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

43 43 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

44 44 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 20 th 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

45 Backup Slides (The Details) 45

46 46 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)

47 47 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

48 48 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 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

50 50 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

51 51 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 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 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

54 54 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 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 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 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

58 58 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)

59 59 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 60 Leyte Island Assault Continues LTG Krueger moves 6 th 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

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