Chapter I: Front Matter

U. S. MARINE OPERATIONS IN KOREA

1950–1953

VOLUME II

_The Inchon-Seoul Operation_

by

LYNN MONTROSS

and

CAPTAIN NICHOLAS A. CANZONA, USMC

Historical Branch, G-3
Headquarters U. S. Marine Corps,
Washington, D. C., 1955

Foreword

The Inchon Landing was a major amphibious operation, planned in record time and executed with skill and precision. Even more, it was an exemplification of the fruits of a bold strategy executed by a competent force. The decision to attack at Inchon involved weakening the line against enemy strength in the Pusan Perimeter in order to strike him in the rear. It involved the conduct of an amphibious attack under most difficult conditions of weather and geography.

The stakes were high and the risk was fully justified. Had it not been for the intervention of the Chinese Communist Army, the offensive generated by the Inchon attack would have resulted in a complete victory for our arms in Korea. A study of the record of this operation will disclose, with arresting clarity, the decisive power that is to be found in highly trained amphibious forces when their strength is applied at the critical place and time.

LEMUEL C. SHEPHERD, JR.,
_General, U. S. Marine Corps_,
_Commandant of the Marine Corps_.

Preface

This is the second volume of a series dealing with United States Marine Operations in Korea during the period 2 August 1950 to 27 July 1953. Volume II presents in detail the operations of the 1st Marine Division and the 1st Marine Aircraft Wing as a part of X Corps, USA, during and immediately following the Inchon Landing on 15 September 1950.

In order to tell a complete story of this historic amphibious operation, the authors have described the mobilization of the Marine Corps reserves to form the components of the Division and Aircraft Wing; the movement to the staging area and the hurried planning for an amphibious landing; the withdrawal of the 1st Provisional Brigade and Marine Air Group 33 from the embattled Pusan Perimeter to amalgamate with the larger force for D-day at Inchon; the seizure of Seoul and its environs, and finally the withdrawal on 7 October to prepare for the Wonsan operation.

Again, this is primarily a Marine Corps story. Activities of other services are presented in sufficient detail only to set this operation in its proper perspective.

Grateful acknowledgment is made for the valuable information furnished by the scores of officers and men consulted by interview or letter and for the assistance provided by the Current History Branch of the Office of the Chief of Military History, Department of the Army.

Maps included herein were prepared by the Reproduction Section, Marine Corps Schools, Quantico, Virginia.

T. A. WORNHAM,
_Major General, U. S. Marine Corps_,
_Assistant Chief of Staff, G-3_.

Contents

_Page_
I The Communist Challenge 1

Authorization of Marine Brigade--First Conference on
Inchon Landing--General Shepherd in Tokyo--Request
for a Marine Division--America’s Force-in-Readiness--
Planning for the Pohang Landing

II The Minute Men of 1950 17

Expansion to Full Peace Strength--Mobilization of
Marine Corps Reserve--The Influx at Camp Pendleton--
Embarkation of 1st Marine Division--Build-up of 7th
Marine Regiment--Staff Groups Flown to Japan

III Operation Plan CHROMITE 37

Interview with General MacArthur--Conferences in
Tokyo--Inception of X Corps--Final Conference on
Inchon--Brigade Victory in Korea--The Marine Amphibious
Mission

IV The Planning Phase 53

Working Around the Clock--X Corps Scheme of Maneuver--
Intelligence Planning for Inchon--The Landing
Force Plan--Naval Gunfire and Rockets--Plans for Air
Support

V Embarkation and Assault 73

Landing of 1st Marine Division--Plan to Seize Kimpo
Airfield--Shipping Assigned to Marines--Movement to
the Objective Area--Strikes and Bombardments--Marine
Landings on GREEN Beach--The Two Harbor Islands
Secured

VI Hitting the Beaches 97

The Assault Plan--Beginning the Ship-to-Shore Movement--
Seizure of Cemetery Hill--RED Beach Secured--LSTs
under Enemy Fire--Fighting on Observatory Hill--1st
Marines on BLUE Beach--Ending the Ship-to-Shore
Movement--Seizure of the 0-1 Line

VII Securing the Beachhead 125

Supplies on RED and BLUE Beaches--Surgical Teams on
the Beaches--Artillery and Tank Operations--The Attack
on D-plus 1--Advance to the Force Beachhead Line--
Displacement Ashore of Division CP

VIII On to Kimpo 143

Operations on Other Korean Fronts--Landing of RCT-7
in Japan--Destruction of NKPA Tank Column--General
MacArthur Visits the Front--The Drive to Kimpo
Airfield--Action at 5th Marines CP--Enemy Counterattack
at Kimpo

IX Marine Air Support 165

Helicopters and OYs in Support--Marine Air Units at
Kimpo--Progress of Eighth Army Offensive--Division
CP Displaces to Oeoso-Ri--Advance of RCT-1 to Sosa--
Reports of Enemy Build-up--Preparations for Crossing
the Han

X Crossing the Han 187

Swimming Team Leads the Way--Marine LVTs Grounded
in Mud--Daylight Assault Crossing by 3/5--Departure of
General MacArthur--Supporting Arms of Bridgehead--
Command Ashore Assumed by X Corps

XI The Fight For Yongdungpo 205

Three Hills Taken by 1/5-Enemy Minefields Encountered--
NKPA Counterattacks of 20 September--Recapture
of Hills 80 and 85--1st Marines in Position--Assault
of Yongdungpo--Able Company on a Limb--Yongdungpo
Secured

XII Main Line of Resistance 233

Three Hills Designated 105--RCT-7 North of the Han--
Attack Continued by RCT-5--Modified Plan of Corps
Attack--Climax of the Marine Assault--The Epic of Dog
Company--River Crossing of RCT-1

XIII Seoul as a Battlefield 253

Two More River Crossings--Division Attack of 25
September--Night Pursuit Ordered by Corps--Renewal of
Drive Through Seoul--Entrapment of Dog Company,
RCT-7--Last Fight on Hill 296--1st Marines in the
Heart of Seoul--Objective Secured

XIV The Drive to Uijongbu 281

Operations of 28 September--Liberation Ceremony at
Seoul--Crumbling of NKPA Resistance--RCT-7 and the
Battle for Uijongbu--Last Days of Inchon-Seoul
Operation--Summaries and Conclusions--MacArthur’s Report
to United Nations

_Appendixes_

A Glossary of Technical Terms and Abbreviations 299

B Build-up of 1st Marine Division (Reinf) 303

C Task Organization of Marine Division for Inchon Landing 305

D Supplies and Equipment for Inchon 311

E Task Organization, Joint Task Force Seven 313

F Final Troop List of Division for the Inchon Landing 321

G Summary of Operation Orders Issued by 1st Marine Division for
the Inchon-Seoul Campaign 323

H Enemy Units During the Inchon-Seoul Campaign 325

I Congratulatory Messages 329

J Casualties During the Inchon-Seoul Campaign 333

K Comments on Close Air Support Provided By 1st Marine Aircraft
Wing 335

L Presidential Unit Citation 339

Bibliography 341

Index 347

Illustrations

_Photographs_

Sixteen-page sections of photographs follow pages 68 and 180.

_Maps and Sketches_

_Page_
NKPA Gains, 30 June-1 August 1950 29

Plan for Inchon Assault 68

Movements to the Objective Area 82

Seizure of Wolmi-do 89

Plan for Inchon Assault 99

Seizure of Red Beach 109

Seizure of Blue Beach 119

Marine Attacks D + 1 137

NK Counterattack Ascom City, 17 September 149

The Drive to Kimpo 154

NK Counterattack Kimpo Air Field, 18 September 162

Advance by 1st Marines, 17 September 174

Capture of Sosa by 1st Marines, 18 September 179

General Situation, 18 September 182

Han River Crossing and Seizure of Hill 125 189

Action on 19 September 207

Action on 20 September 218

Assault on Yongdungpo 224

Dike Defense--Company A, 1st Marines 230

Approaching the Enemy MLR, 5th Marines, 21 September 237

Smashing the MLR, 5th Marines, 22–24 September 242

Seoul Assault Plan 265

The Battle of Seoul 266

Action North of Seoul, 7th Marines 269

Pursuit of the NKPA and Capture of Uijongbu 288