Marine Corps Historical Collection_Closing In: Marines in the Seizure of Iwo Jima

_After 24 days of the most bitter battle in the history of the Marine

Corps to that date, on 14 March 1945, the colors were raised once again

on Iwo Jima to signify the occupation of the island, although the

battle was still raging in the north. The official end of the campaign

would not be until 14 days later, on 26 March._]

The killing continued in the north. The 5th Marine Division entered The

Gorge, an 800-yard pocket of incredibly broken country which the troops

would soon call “Death Valley.” Here General Kuribayashi maintained his

final command center in a deep cave. Fighting in this ungodly landscape

provided a fitting end to the battle--nine endless days of cave-by-cave

assaults with flamethrowers and demolitions. Combat engineers used

8,500 tons of explosives to detonate one huge fortification. Progress

was slow and costlier than ever. General Rockey’s drained and depleted

regiments lost one more man with every two yards gained. To ease the

pressure, General Schmidt deployed the 3d Marine Division against

Kitano Point in the 5th Division zone.

Colonel Hartnoll J. Withers directed the final assault of his 21st

Marines against the extreme northern tip of the island. General

Erskine, pneumonia be damned, came forward to look over his shoulder.

The 21st Marines could see the end, and their momentum proved

irresistible. In half a day of sharp fighting they cleared the point of

the last defenders. Erskine signalled Schmidt: “Kitano Point is taken.”

Both divisions made serious efforts to persuade Kuribayashi to

surrender during these final days, broadcasting appeals in Japanese,

sending personal messages praising his valor and urging his

cooperation. Kuribayashi remained a samurai to the end. He transmitted

one final message to Tokyo, saying “we have not eaten or drunk for five

days, but our fighting spirit is still running high. We are going to

fight bravely to the last.” Imperial Headquarters tried to convey the

good news to him that the Emperor had approved his promotion to full

general. There was no response from Iwo Jima. Kuribayashi’s promotion

would be posthumous. Fragmentary Japanese accounts indicate he took his

own life during the night of 25-26 March.

In The Gorge, the 5th Marine Division kept clawing forward. The

division reported that the average battalion, which had landed with

36 officers and 885 men on D-day, now mustered 16 officers and 300

men, including the hundreds of replacements funneled in during the

fighting. The remnants of the 1st Battalion, 26th Marines, and the 1st

Battalion, 28th Marines, squeezed the Japanese into a final pocket,

then overwhelmed them.

It was the evening of 25 March, D+34, and the amphibious assault on

the rocky fortress of Iwo Jima finally appeared over. The island grew

strangely quiet. There were far fewer illumination shells. In the

flickering false light, some saw shadowy figures, moving south, towards

the airfield.

General Schmidt received the good news that the 5th Marine Division had

snuffed out the final enemy cave in The Gorge on the evening of D+34.

But even as the corps commander prepared his announcement declaring the

end of organized resistance on Iwo Jima, a very well-organized enemy

force emerged from northern caves and infiltrated down the length of

the island. This final spasm of Japanese opposition still reflected

the influence of Kuribayashi’s tactical discipline. The 300-man force

took all night to move into position around the island’s now vulnerable

rear base area, the tents occupied by freshly arrived Army pilots of

VII Fighter Command, adjacent to Airfield No. 1. The counterattacking

force achieved total surprise, falling on the sleeping pilots out of

the darkness with swords, grenades, and automatic weapons. The fighting

was as vicious and bloody as any that occurred in Iwo Jima’s many

arenas.

The surviving pilots and members of the 5th Pioneer Battalion

improvised a skirmish line and launched a counterattack of their

own. Seabees and elements of the redeploying 28th Marines joined the

fray. There were few suicides among the Japanese; most died in place,

grateful to strike one final blow for the Emperor. Sunrise revealed the

awful carnage: 300 dead Japanese; more than 100 slain pilots, Seabees,

and pioneers; and another 200 American wounded. It was a grotesque

closing chapter to five continuous weeks of savagery.

The 5th Marine Division and the 21st Marines wasted no time in

backloading on board amphibious ships. The 9th Marines, last of the VAC

maneuver units to land, became the last to leave, conducting two more

weeks of ambushes and combat patrols. The 147th Infantry inherited more

of the same. In the first two months after the Marines left, the Army

troops killed 1,602 Japanese and captured 867 more.

[Sidebar (page 37): The Marines’ Zippo Tanks

To the Marines on the ground, the Sherman M4A3 medium tank equipped

with the Navy Mark I flame thrower seemed to be the most valuable

weapon employed in the battle of Iwo Jima.

The Marines had come a long way in the tactical use of fire in the 15

months since Tarawa, when only a handful of backpack flame throwers

were available to combat the island’s hundreds of fortifications. While

the landing force still relied on portable flame throwers, most Marines

could see the value of marrying the technology with armored vehicles

for use against the toughest targets. In the Marianas, the Marines

modified M3A1 light tanks with the Canadian Ronson flame system to good

effect; the problems came from the vulnerability of the small vehicles.

At Peleliu, the 1st Marine Division mounted the improvised Mark I

system on a thin-skinned LVT-4; again, vehicle vulnerability limited

the system’s effectiveness. The obvious solution seemed to be to mount

the flame thrower in a medium tank.

The first modification to Sherman tanks involved the installation of

the small E4-5 mechanized flame thrower in place of the bow machine

gun. This was only a marginal improvement; the system’s short range,

modest fuel supply, and awkward aiming process hardly offset the loss

of the machine gun. Even so, each of the three tank battalions employed

E4-5-equipped Shermans during Iwo Jima.

The best solution to marrying effective flame projection with

mechanized mobility resulted from an unlikely inter-service task force

of Seabees, Army Chemical Warfare Service technicians, and Fleet Marine

Force tankers in Hawaii before the invasion. According to Lieutenant

Colonel William R. Collins, commanding the 5th Tank Battalion, this

inspired group of field-expedient tinkerers modified the Mark I flame

thrower to operate from within the Sherman’s turret, replacing the

75mm main gun with a look-alike launch tube. The modified system

could thus be trained and pointed like any conventional turret gun.

Using napalm-thickened fuel, the “Zippo Tanks” could spew flame up

to 150 yards for a duration of 55-80 seconds, both quantum tactical

improvements.

Unfortunately, the _ad hoc_ modification team had only sufficient

time and components to modify eight M4A3 tanks with the Mark I flame

system; four each went to the 4th and 5th Tank Battalions. The 3d Tank

Battalion, then staging in Guam, received neither the M4A3 Shermans

nor the field modifications in time for Iwo Jima, although a number of

their “A2” tanks retained the E4-5 system mounted in the bow.

The eight modified Sherman flame tanks proved ideal against Iwo Jima’s

rugged caves and concrete fortifications. The Japanese feared this

weapon greatly; time and again suicide squads of “human bullets” would

assail the flame tanks directly, only to be shot down by covering

forces or scorched by the main weapon. Enemy fire and the rough terrain

took their toll on the eight flame tanks, but maintenance crews worked

around the clock to keep them functional.

In the words of Captain Frank C. Caldwell, a company commander in the

26th Marines: “In my view it was the flame tank more than any other

supporting arm that won this battle.” Tactical demands for the flame

tanks never diminished. Late in the battle, as the 5th Marine Division

cornered the last Japanese defenders in “The Gorge,” the 5th Tank

Battalion expended napalm-thickened fuel at the rate of 10,000 gallons

per day. The division’s final action report stated that the flame tank

was “the one weapon that caused the Japs to leave their caves and rock

crevices and run.”

[Illustration: _A Marine flame tank, also known as a “Ronson,” scorches

a Japanese strongpoint. The eight M4A3 Shermans equipped with the Navy

Mark I flame-thrower proved to be the most valuable weapons systems on

Iwo Jima._

Department of Defense Photo (USMC) 140758

]

[Sidebar (page 42): Iwo’s Fire Brigades: The Rocket Detachments

Attached to the assault divisions of the landing force at Iwo Jima

were provisional rocket detachments. The infantry had a love-hate

relationship with the forward-deploying little rocket trucks and their

plucky crews. The “system” was an International one-ton 4×4 truck

modified to carry three box-shaped launchers, each containing a dozen

4.5-inch rockets. A good crew could launch a “ripple” of 36 rockets

within a matter of seconds, providing a blanket of high explosives

on the target. This the infantry loved--but each launching always

drew heavy return fire from the Japanese who feared the “automatic

artillery.”

The Marines formed an Experimental Rocket Unit in June 1943 and first

deployed rail-launched barrage rockets during the fighting in the

upper Solomons. There the heavily canopied jungles limited their

effectiveness. Once mounted on trucks and deployed to the Central

Pacific, however, the weapons proved much more useful, particularly

during the battle of Saipan. The Marines modified the small trucks by

reinforcing the tail gate to serve as a blast shield, installing a

hydraulic jack to raise and lower the launchers, and applying gravity

quadrants and elevation safety chains. Crude steel rods welded to the

bumper and dashboard helped the driver align the vehicle with aiming

stakes.

Treeless, hilly Iwo Jima proved an ideal battleground for these

so-called “Buck Rogers Men.” At Iwo, the 1st Provisional Rocket

Detachment supported the 4th Marine Division and the 3d Detachment

supported the 5th Division throughout the operation (the 3d Division

did not have such a unit in this battle). Between them, the two

detachments fired more than 30,000 rockets in support of the landing

force.

The 3d Detachment landed over Red Beach on D-day, losing one vehicle

to the surf, others to the loose sand or heavy enemy fire. One vehicle

reached its firing position intact and launched a salvo of rockets

against Japanese fortifications along the slopes of Suribachi,

detonating an enemy ammunition dump. The detachment subsequently

supported the 1st Battalion, 28th Marines’ advance to the summit, often

launching single rockets to clear suspected enemy positions along the

route.

As the fighting moved north, the short range, steep angle of fire, and

saturation effect of the rocket launchers kept them in high demand.

They were particularly valuable in defilade-to-defilade bombardments

marking the final punctuation of pre-assault prep fires. But their

distinctive flash and telltale blast also caught the attention of

Japanese artillery spotters. The rocket trucks rarely remained in one

place long enough to fire more than two salvos. “Speedy displacement”

was the key to their survival. The nearby infantry knew better than to

stand around and wave goodbye; this was the time to seek deep shelter

from the counterbattery fire sure to follow.

[Illustration: _The positions from which rocket troops launched salvos

of 4.5-inch rockets became very unhealthy places, indeed, as Japanese

artillery and mortars zeroed in on the clouds of smoke and dust

resulting from the firing of the rockets._

Department of Defense Photo (USMC) 111100

]

[Sidebar (page 44): Amphibious Logistical Support at Iwo Jima

The logistical effort required to sustain the seizure of Iwo Jima was

enormous, complex, largely improvised on lessons learned in earlier

Marine Corps operations in the Pacific, and highly successful. Clearly,

no other element of the emerging art of amphibious warfare had improved

so greatly by the winter of 1945. Marines may have had the heart and

firepower to tackle a fortress-like Iwo Jima earlier in the war, but

they would have been crippled in the doing of it by limitations in

amphibious logistical support capabilities. These concepts, procedures,

organizations, and special materials took years to develop; once in

place they fully enabled such large-scale conquests as Iwo Jima and

Okinawa.

For the Iwo Jima operation, VAC had the 8th Field Depot, commanded

by Colonel Leland S. Swindler. The depot was designed to serve as

the nucleus of the shore party operation; the depot commander was

dual-hatted as the Shore Party Commander of the Landing Force, in

which capacity he was responsible for coordinating the activities of

the division shore parties. The timing of the logistics support at Iwo

Jima proved to be well conceived and executed. Liaison teams from the

8th Field Depot accompanied the 4th and 5th Divisions ashore. On D+3,

units of the field depot came ashore, and two days after this, when VAC

assumed control on shore, the field depot took over and the unloading

continued without interruption.

The V Amphibious Corps at Iwo Jima used every conceivable means of

delivering combat cargo ashore when and where needed by the landing

force. These means sequentially involved the prescribed loads and

units of fire carried by the assault waves; “hot cargo” preloaded

in on-call waves or floating dumps; experimental use of “one-shot”

preloaded amphibious trailers and Wilson drums; general unloading;

administrative unloading of what later generations of amphibians

would call an “assault follow-on echelon”; and aerial delivery of

critically short items, first by parachute, then by transports landing

on the captured runways. In the process, the Navy-Marine Corps team

successfully experimented with the use of armored bulldozers and sleds

loaded with hinged Marston matting delivered in the assault waves to

help clear wheeled vehicles stuck in the soft volcanic sand. In spite

of formidable early obstacles--foul weather, heavy surf, dangerous

undertows, and fearsome enemy fire--the system worked. Combat cargo

flowed in; casualties and salvaged equipment flowed out.

Shortages appeared from time to time, largely the result of the Marines

on shore meeting a stronger and larger defense garrison than estimated.

Hence, urgent calls soon came for more demolitions, grenades, mortar

illumination rounds, flame-thrower recharging units, and whole blood.

Transport squadrons delivered many of these critical items directly

from fleet bases in the Marianas.

Field medical support at Iwo Jima was a model of exhaustive planning

and flexible application. The Marines had always enjoyed the finest

immediate medical attention from their organic surgeons and corpsmen,

but the backup system ashore at Iwo Jima, from field hospitals

to graves registration, was mind-boggling to the older veterans.

Moderately wounded Marines received full hospital treatment and

rehabilitation; many returned directly to their units, thus preserving

at least some of the rapidly decreasing levels of combat experience in

frontline outfits. The more seriously wounded were treated, stabilized,

and evacuated, either to offshore hospital ships or by air transport to

Guam.

The Marines fired an unprecedented half million artillery rounds in

direct and general support of the assault units. More rounds were lost

when the 5th Marine Division dump blew up. The flow never stopped. The

Shore Party used DUKWs, LVTs, and larger craft for rapid offloading

of ammunition ships dangerously exposed to Iwo Jima’s enemy gunners.

Marine Corps ammunition and depot companies hustled the fresh munitions

ashore and into the neediest hands.

Lieutenant Colonel James D. Hittle, USMC, served as D-4 of the 3d

Marine Division throughout the battle of Iwo Jima. While shaking his

head at the “crazy-quilt” logistic adaptations dictated by Iwo’s

geography, Hittle saw creative staff management at all levels. The 3d

Division, earmarked as the reserve for the landing, found it difficult

to undertake combat loading of their ships in the absence of a scheme

of maneuver on shore, but the staff made valid assumptions based on

their earlier experiences. This paid huge dividends when the corps

commander had to commit the 21st Marines as a separate tactical unit

well in advance of the division. Thanks to foresightful combat loading,

the regiment landed fully equipped and supported, ready for immediate

deployment in the fighting.

To augment the supplies coming across the beach, the 3d Division staff

air officer “appropriated” a transport plane and made regular runs to

the division’s base in Guam, bringing back fresh beef, mail, and cases

of beer. The 3d Division G-4 also sent his transport quartermaster

(today’s embarkation officer) out to sea with an LVT-full of war

souvenirs; these were bartered with ship’s crews for donations of fresh

fruit, eggs, bread--“we’d take anything.” General Erskine distributed

these treats personally to the men in the lines.

Retired Brigadier General Hittle marveled at the density of troops

funnelled into the small island. “At one point we had 60,000 men

occupying less than three-and-a-half square miles of broken terrain.”

These produced startling neighbors: a 105mm battery firing from the

middle of the shore party cantonment; the division command post sited

1,000 yards from Japanese lines; “giant B-29s taking off and landing

forward of the CP of an assault regiment.”

In the effort to establish a fresh-water distilling plant, Marine

engineers dug a “well” near the beach. Instead of a source of salt

water the crew discovered steaming mineral water, heated by Suribachi’s

supposedly dormant volcano. Hittle moved the 3d Division distilling

site elsewhere; this spot became a hot shower facility, soon one of the