Sea Power and Maritime Affairs
Lesson 12: The US Navy in
the Pacific, 1941-1945
Learning Objectives

Comprehend the political and economic forces that led Japan to strike at Pearl
Harbor and the Far East.

Comprehend the Japanese strategy for an early victory and their concept of the
postwar Pacific power balance.

Comprehend the impact of Pearl Harbor and the subsequent Battles of Coral
Sea and Midway on the transformation of the aircraft carrier's role in naval
warfare.

Know the significant highlights of the evolution of US operational strategy in
the Pacific, including major battles or campaigns and instances where strategy
was flawed or ambiguous.

Know the strategic significance of the employment and refinement of
amphibious landing tactics by the US Navy and US Marine Corps.

Comprehend the reasons the geopolitical world order was changed as a result of
Japan’s actions in striking at the Western powers in 1941.
Background Information

Japanese-American Relations
tense: Japan challenged
America’s “Open Door”
policy by attacking
Manchuria in 1931.
 In 1937, Japanese expansion
in China resulted in attack on
American gunboat, the
Panay, by Japanese aircraft.
 Roosevelt adopted economic
sanctions leading to an oil
embargo by Americans,
British and Dutch (July 1941)
Background Information

The Japanese struck for the oilrich Dutch East
Indies(Indonesia), Singapore,
and the surrounding Britishowned Malaya, Thailand, the
Philippines, and Hong Kong.
 The Japanese camouflaged their
plans with diplomatic
negotiations in Washington.
The United States expected an
assault somewhere in the
Pacific because cryptanalysts, in
a technique called “Magic,” had
broken the Japanese Diplomatic
Code.
Background Information

The attack on Pearl
Harbor surprised the
Americans, who had
not anticipated a strike
so far east or one
mounted solely by
carrier-born aircraft.
Japan WWII Strategy





Secure Resources in Southeast Asia
Create Greater East Asia Co-prosperity Sphere (Like
Asuan Monroe Doctrine)
Attempt to Fight Limited War (Pearl Harbor is major error)
Create defense perimeter to force costly frontal assualts
Negotiate when the US is exhausted/frustrated by
casualties
Pearl Harbor: Japan’s Plan

Southern drive into
Indochina and Dutch East
Indies for oil.
 Strike at Philippines and
Singapore to knock out
local American and British
Forces.
US WWII Strategy

Secure line of Communications to Australia
– Solomons/ Guadal Canal (6 month campaign)

Two Pronged Offensive: South and Central Pacific
– Meet at Philippines

Island Hopping/ Leapfrogging
US WWII Strategy

Island Hopping/ Leapfrogging
– Rather than engage sizable Japanese garrisons, these operations
–
–
–
–
–
–
were designed to cut them off
let them "whither on the vine.”
approach of bypassing Japanese strong points, such as Truk, was
applied on a large scale as Allies moved across the central Pacific.
Known as "island hopping," US forces moved from island to
island, using each as a base for capturing the next.
Seized one or two key Islands in a chain, destroyed Japanese air
and naval units on neighboring Islands
Japanese troops were thus isolated, unable to affect the war
Far fewer US casualties and less time than Japanese anticipated
US WWII Strategy

Key is Fast Carrier Striking force
– Large Aircraft Carriers (CV) of 20,000 – 33,000 tons with 80 –
100 Aircraft and over 30 knots speed
– Enormous firepower (60 bomber aircraft with bombs or torpedoes
– Vulnerability is wooden flight decks, fire danger when hit

Tactics
– carrier raids hit and run
– carrier versus carrier battles
– amphibious landing support.

Forces at the Start of WWII
– Japan 10 CV’s:; US has 7 CV’s
US WWII Strategy

US Advantages
– Produce more ships and have more man-power
– US builds 14 CV’s, 10 BB’s dozens of Cruisers and Destroyers
and Dozens of Escort and Light Carriers
– Japan only 4 CV’s , 10 Light Carriers

MAGIC program allows US to read Japanese Codes
– Not completely deciphered but critical to US victory

Radar installed on most US ships and used for fire
control
– Also used by submarines
Japanese Advantages

Early Air superiority
– Planes are faster, more maneuverable, but vulnerable due to
–
–
–
–
lack of armor and self sealing gas tanks
Superior Night vision devices at start of war
More Aircraft carriers at start of War
Larger surface ships BB’s, CA,s DD’s due to Washington
Treaty violations before WWII
Better torpedoes and these torpedoes were mounted on CA’s
as well as DD’s (Critical during Guadalcanal/Solomons
Campaign)
Pearl Harbor
Pearl Harbor — Japanese Plans

Attack on Pearl Harbor conceived by Admiral Yamamoto:
– Great risk — U.S. would surely enter the war.
– Greater potential gain — U.S. Pacific Fleet would be knocked out
of the war.


Japan would then consolidate gains throughout China and the Pacific.
Possibility of U.S. agreeing to Japanese territorial gains to make peace.
– Good possibility of U.S. involvement in Europe as well.


Will drain naval resources from Pacific Ocean.
U.S. Atlantic Fleet already involved in convoy escort against U-boats.
The Attack
Aftermath of Pearl Harbor

Battleship fleet effectively destroyed

Carriers survive and become new capital ships
– Submarines, repair facilities, and oil tanks also left
unharmed by attack

Result generally not anticipated by American naval
planners before Pearl Harbor
– Naval tactics change to support carrier strikes
– Circular formations developed to protect carriers
Aftermath of Pearl Harbor

U.S. declares war on Japan
– “Day of Infamy” - Franklin Delano Roosevelt

Hitler declares war on the U.S.

American public opinion changes in favor of war
U.S. Defensive Organization/ Plans

Admiral Chester W. Nimitz relieves Kimmel as
Commander in Chief, U.S. Pacific Fleet

Nimitz - Commander in Chief Pacific Ocean Areas
–

Includes North, Central, and South Pacific Areas
MacArthur - Commander in Chief Southwest Pacific Area
–
–
Australia, New Guineau, East Indies, and Philippines
Fleet elements in this zone remained under Nimitz's control
U.S. Defensive Organization/
Plans

Controversial command structure
–

No common superior -- two separate wars in the Pacific
Overwhelming U.S. industrial and logistical
superiority
–
Allows divided command until forces converge on
Philippines in 1944
Island Hopping

MacArthur leapfrogs up coast of New Guinea
 Nimitz Island Hopping across central Pacific
 Goal is to create secure supply line to seize
Marianas Islands
– Establish airfields there for long range bombers
to attack Japan then Meet MacArthur at the
Phillipines

Despite “Germany First” Policy the Two Commanders get
all the resources they need
Submarines in the Pacific

Unrestricted Submarine Warfare
– Commences against Japan immediately following
Pearl Harbor attack by order of CNO Admiral King.
“We shall never forget that it was our submarines
that held the lines against the enemy while our
fleets replaced losses and repaired wounds.”
- Fleet Admiral Chester Nimitz, 1947
U.S. Submarine Warfare

Simultaneously with Dual advance, US conducts war on
commerce
 Unrestricted Submarine Warfare ordered immediately
after Pearl Harbor -- new role for U.S. submarines
 Early operational problems - 1942-43:
– Undependable torpedoes - poorly designed magnetic fusing.



Refuse to test them ($10,000 a piece)
Many commanders were excessively cautious.
US Fleet subs best of the war
–
55 Days at sea, 24 torpedoes, fast diving, air conditioned
U.S. Submarine Warfare

Don’t fix problems to 1943
–
–
–
–

1/3 of Commanders relieved and replaced with aggressive younger ones
Abandon scout role and switch to night attacks
Target all ships
 Eventually emphasize oil tankers
Finally fix torpedoes that ran too deep and failed to explode
1944 have good equipment, right doctrine
–
–
–
–
Also crack the Japanese Merchant ship code (Maru Code)
Japanese refuse to convoy (defensive war is not consistent with Warrior Code
Refuse to build escorts until 1943
By 1945 Japanese Merchant Marine is totally destroyed
Japanese Submarine Warfare

Long Lance torpedo - smaller variant for submarines
 I-Boat is big, slow to submerge and noisy
 Focused attacks on U.S. warships and avoided supply ships
–
–

Used to screen and scout for battle fleets
“Warrior ethos” of Japanese naval leaders
Used for supply of bypassed garrisons and “exotic”
missions
Japanese Submarine Warfare

Battle of Midway
–
–

Guadalcanal Campaign
–
–

Failed to intercept U.S. carrier forces
Torpedoed USS Yorktown under tow
USS Saratoga torpedoed January 1942
USS Wasp sunk
USS Indianapolis sunk -- July 1945 - shark
attacks
Mitsubishi A6M “Zero”
TBD-1 Devastator Torpedo Bombers
USS Yorktown (CV 5)
SBD-3 Dauntless Dive Bombers
F4F Wildcats
USS Enterprise (CV 6)
USS Hornet (CV 8)
Captain Marc Mitscher, Commanding Officer
USS Yorktown (CV 5)


Damaged by air strikes on 4 June.
Sunk by submarine torpedo attack on 7 June.
Japanese Carriers
Kaga, Akagi, and Soryu
USS Yorktown (CV 5)
USS Yorktown (CV 5)
Break Time…………….
When We Resume: The US Navy and the Offensive Phase
A6M “Zero” or “Zeke”
Fighter
U.S. Aircraft Production

Japan and Germany had early advantage in air war:
– Messerschmit ME-109
– Mitsubishi A6M Zero

U.S. aircraft industry produces higher performance
aircraft
– American industrial base allows rapid and mass production

New flight training programs developed

U.S. gains advantage in air warfare

Air supremacy eventually established in both European
and Pacific theaters
F2A “Buffalo”
Fighter
F4F “Wildcat”
Fighter
Wildcats on the Prowl
F6F “Hellcat”
Fighter
F4U Corsair
Fighter
SBD “Dauntless”
Dive Bomber
SB2C “Helldiver”
Dive Bomber
TBF “Avenger”
Torpedo Bomber
PBY “Catalina”
Scout
Prelude to Guadalcanal

Japanese leadership shocked by defeat at Midway

Cancel plans to take Fiji, Samoa, and New Caledonia

Must proceed with plan to take Port Moresby

Within bomber range of major naval operating base
at Rabaul

Japanese begin building airfield at Guadalcanal
Prelude to Guadalcanal

Nimitz moves to reinforce South Pacific Area
– Protect vital sea lines of communication with Australia.
– Vice Admiral Robert L. Ghormley

Commander South Pacific Ocean Area (Subordinate
to Nimitz).
– Two bases established in New Hebrides.
Army - Navy Dispute

MacArthur proposes retaking Rabaul
– Wants Navy to let him borrow First Marine Division

Admiral King
– Objects to Macarthur's plan
– Proposes step-by-step advance through Solomons to re-take
Rabaul.
– Nimitz and Ghormley in command with Marines making
amphibious assaults and Navy providing support.

Army forces used as garrisons for islands
Operation Watchtower

Compromise Three-Stage Plan of Operations

Initial advance in Eastern Solomons under Nimitz

Boundary between Areas moved west

MacArthur takes command after Tulagi secured
Gudalcanal Campaign
Aug 1942-Feb 1943
Guadalcanal

Whoever controlled an airfield would control air
over the Solomons

Vital SLOC

For both sides it symbolized offensive rather than
defensive warfare
Force Commanders

Admiral Robert L. Ghormley overall command of
Watchtower

Rear Admiral Richmond Kelly Turner Amphibious Forces

Vice Admiral Frank Jack Fletcher carrier group
– Provided support against Japanese fleet during day
General
Archer Vandegrift

Commander - First
Marine Division

Amphibious landing
virtually unopposed
–
Marines take Henderson
Field - “Cactus Air Force”.
Guadalcanal River Crossing
“See-Saw” Pattern

Japan dominates nighttime action.
–

“Tokyo Express” down “The Slot” into “Ironbottom
Sound”
U.S. dominates daytime with shore and carrier
aircraft
Actions

Battle of Savo Island, 8-9 August 1942

Battle of the Eastern Solomons, 24 August
1942

Battle of the Santa Cruz Islands, 26-27
October, 1942

“Naval Battle of Gudalcanal”, 12-13
November, 1942
Guadalcanal Campaign

Battle of Savo Island - Allies
defeated in night surface action

Battle of the Eastern Solomons carrier battle
–
–
USS Enterprise damaged by
bombers
USS Wasp sunk and Saratoga
damaged by Japanese submarines
Battle of Santa Cruz Islands

Halsey relieves Ghormley - 18 October 1942

Rear Admiral Thomas C. Kinkaid

Hornet sunk and Enterprise damaged
–
No operational carriers left

Zuiho and Shokaku badly damaged

Tactical defeat by strategic victory?…maybe
Naval Battle

Rear Admiral Willis A. Lee
– uses RADAR to his advantage to win nighttime
naval battle

Washington and South Dakota outfight
Japanese battleships
– Warships flee
– Transports beach themselves
Guadalcanal Campaign

1st Marine Division relieved by Army’s 25th Infantry
Division

Japanese forces evacuate Guadalcanal

U.S. forces begin advance up Solomon Islands
– Land-based airfields established

Marine Corps’ “Black Sheep” Squadron (VMF-214)
– Commanded by Maj Greg “Pappy” Boyington
• Medal of Honor Recipient

MacArthur drives Japanese from eastern Papua
–
Captures main Japanese base at Buna
Aftermath

Both sides suffered heavy losses
– U.S loses more tonnage at sea, carriers
– Japan loses more lives

Japan allowed to dominate sea at night while U.S.
dominates day

Battle drags on from Aug 42- Feb 43
Aftermath

MacArthur successful in driving Japanese from
Papuan Peninsula
– By Feb 43 Jap plans for offensives in S. and W Pacific
stopped cold

King uses Casablanca Conference to allocate more
resources to Pacific
Reconquest of Attu and Kiska
Aleutian Islands
(January - May 1943)

No real threat to security.

Necessary to end Japanese control of American territory
for political reasons.

Battle of the Komondorskis

–
Last classic surface ship battle.
–
Americans attack heavily guarded Japanese convoy.
Minimal resistance on Attu, none on Kiska.
Operation Cartwheel

The Solomons Campaign

Halsey goes to work for McArthur
– Leads Amphibious Assault from Guadalcanal along Solomons

McArthur wants direct assault on Rabaul
– King and Marshall overrule him
– Capture every island BUT Rabaul to isolate it

Rabaul becomes isolated and insignificant
–
On to the Phillipines (October 1944)
The Defeat of Japan
Objective: The Philippines and the penetration of the
Japanese inner defense zone!
The Advance

Pacific “Thrust”
– Amphib support

Vice Admiral
Raymond Spruance

Significant campaigns:
– Gilberts
– Marshalls
– Marianas
Essex
Class
Fast
Carrier
The Gilberts (Tarawa)



New fleet organization
due to new Essex Class
carrier fleet production
Objective to gain airfield
on Betio Island to launch
further attacks in Central
Pacific Drive
3 days cost US > 3,000
marines
Marines at Tarawa
Kwajalein Atoll
Tarawa
The Marshalls


After the Gilberts, concern
for death toll in Marshalls
Nimitz orders RADM
MITSCHER attack on
Airpower
– Destroys Japanese Force



Kwajalein success furthers
to the rest of the islands
Total Marshall loss less
than first day of Tarawa
Onto Marianas
The Marianas

Draws out Japanese
Fleet
 Battle of Philippine
Sea, 19-20 June 1944
“The Great Marianas
Turkey Shoot”
– 346 Jap planes downed
– 3 Jap carriers sunk
– Classic Mahanian
engagement
Liberation of the Philippines

U.S. advance continues after Marianas Campaign
– Macarthur's forces capture New Guinea

Air strikes in the Phillipines wipe out two hundred
aircraft

Bypass smaller islands and head to Leyte Gulf early
– from 20 December to 20 October
Battle
of
Leyte Gulf
Battle of Leyte Gulf
24-25 October 1944

Largest battle in all of naval history

U.S. command structure remains divided and
confused

U.S. landings in Leyte Gulf
– MacArthur “returns”
Battle
of
Leyte Gulf


“In case opportunity for
destruction of the major portion
of the enemy fleet is offered or
can be created, such destruction
becomes the primary task.”
-- Standing
Order of
Fleet Admiral Nimitz
“Where is, repeat where is,
Task Force 34? The world
wonders.”
-- Nimitz’ (message to
Halsey during the battle.)
Admiral
Marc
Mitscher
Commander
Fast Carrier Task
Force
Battle of Leyte Gulf
Battle of Leyte Gulf

Japanese Combined Fleet divided into three
forces:
– Northern
– Central
– Southern

Japanese defeated in a series of separate
engagements.
– Effective end of Japanese Navy’s ability to control the
sea.
Battle of Leyte Gulf
Japanese Kamikaze Squadrons

Explosives loaded aboard aircraft.
 Japanese pilots fly one-way suicide attack
missions against U.S. fleet.
 First used at Leyte Gulf.
USS Lexington (CV 16)
Essex Class Fast Carrier
Mitscher’s Flagship -- Battle of Leyte Gulf
Admiral
Thomas Kinkaid
Commander
U.S. Seventh Fleet
Battle of Leyte Gulf
The Sands of Iwo Jima
Mount Suribachi
The Road to Japan

Iwo Jima

Okinawa
Iwo Jima

Emergency landing field and fighter escort base desired.
– Midway between Marianas and Tokyo
– Support B-29 strategic bombing of Japan

26,000 casualties
–

General Holland Smith
–

2,400 Emergency landings - 27,000 aircrew
“Iwo Jima was the most savage and most costly battle in the
history of the Marine Corps.”
Admiral Nimitz
–
“Uncommon valor was a common virtue.”
Okinawa Campaign April-June 1945

Staging base for invasion of Kyushu

Joint amphibious operation
– Marines under Army command

Japanese use delaying tactics at the beach
– Continued heavy resistance inland
Okinawa Campaign

Kamikaze raids continue
–
–


34 U.S. ships sunk
4,900 Sailors killed in action
Over 40,000 U.S. casualties
Carrier groups begin raids on Japanese home
islands.
–
U.S. has established complete control of the seas.
USS Benjamin Franklin
-- Damaged in Kamikaze raid during invasion of
Okinawa - March 1945.
Japanese Battleship Yamato
Sunk by U.S. carrier-based aircraft during Okinawa
Campaign.
7 April 1945
U.S. Carrier
Raids
on the
Japanese
Home Islands
July 1945
Manhattan
Project =
Atomic
Bombs

President Truman orders two bombings.
–
–

Hiroshima - 6 August 1945
Nagasaki - 9 August 1945
Believed potential for casualties during a
prolonged struggle for the Japanese home islands
is too high.
Hiroshima
Japan
Surrenders

Japanese officially
surrender aboard USS
Missouri in Tokyo Bay
on 2 September 1945.

MacArthur commands
U.S. army of occupation.
Discussion
Next time: The US Navy in the Early Cold War, 1945-1953