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Assume The Best:  The North Korean Campaign Of 1950
AUTHOR Major Richard P. Mills, USMC
CSC 1990
                EXECUTIVE SUMMARY
THESIS : The American High Command made several critical
assumptions prior to the fall/winter campaign of 1950 and
those assumptions were wrong : It was those faulty
assumptions that assured defeat.
BACKGROUND : On 25 June , 1950 North Korea invaded South
Korea. The North Koreans rapidly defeated the South's
forces. The United Nations approved military intervention
General Douglas MacArthur led a  United States force to
Korea to restore the country . MacArthur conducted the
Inchon operation and turned the tide of the war . By
September 1950 , the UN/US war aims were complete . The US
then  decided to invade North Korea to reunite the
DISCUSSION : In planning the campaign into North  Korea ,
MacArthur made 4 critical assumptions . Those were : (1) The
Chinese would not enter the war, (2) The North's army was
destroyed, (3) American troop performance was improved , and
(4) Total victory was possible . Historical study proves
that none of those assumptions were correct . The planners
of the campaign should have based their assumptions on the
intelligence and operational information they had available.
The incorrect assumptions led to military disaster.
CONCLUSION :  The assumptions covered factors that were
crucial to the campaign . By failing to recognize the true
risks of the invasion , the planners invited military
disaster . The campaign failed because commanders and staffs
failed to live up to their responsibilities.
                 ASSUME THE BEST:
THESIS STATEMENT . The American High  Command made several
critical assumptions prior to the fall/winter campaign of
1950 and those assumptions were wrong : It was those faulty
assumptions that assured defeat .
I.     The Korean War
       A.   The first modern war
       B.   The North Korean Invasion of 25 June, 1950
            1.  Early success by the North
            2.  The North Korean People's Army (NKPA)
       C.   The United Nations' response
II.    The Inchon /  Seoul Campaign
       A.   Turns the tide of the war
       B.   Liberates South Korea
       C.   Leads to a decision to invade North Korea
III.   The Campaign in North Korea
       A.   Planning was based on four faulty assumptions
       B.   Chinese issued warnings about their intentions
       C.   The Rebirth of the NKPA
       D.   US performance
       E.   Concept of total victory
IV.    The Blame
       A.   Other factors were not critical
       B.   Commanders' and staffs' responsibilities
       C.   Consequences
                 ASSUME THE BEST:
     The  Korean  War  stands as  a  milestone  in  American
military history  . It  divides the  wars of  the past  from
modern wars  . In retrospect ,  warfare prior to  1950 seems
almost simple  and straight forward   with a clear  sense of
national  purpose  .  Beginning  with  the  Korean  conflict
warfare has become  a political event with  cloudy goals and
muddy strategy .
     Korea almost defines  modern wars  . There  was never a
declaration of war by the United  States government . It was
the  first war  fought  under  the deadly  consideration  of
atomic  weapons .  The war  was  fought over  a Third  World
country  , for  purely political  reasons  against a  Soviet
equipped  and trained  enemy  .   There were  many  military
successes in  the field ,  although the American  troops had
quite ambivilant feelings about the war  . Finally , the war
became  unpopular at  home  ,  brought down  a  presidential
administration   and  has   never   really  been   resolved.
Unfortunately , America would see its like again .
     The Korean War  began on 25 June , 1950  when the North
Korean People's Army ( NKPA )  swept into South Korea across
the 38th  Parallel .  Their rapid  and overwhelming  success
startled the Western World . In a  matter of days , the NKPA
had  captured the  South's capital  of Seoul  . Using  seven
divisions in its  first echelon and five more  in its second
echelon , the NKPA swept south pushing the Republic of Korea
(  ROK  )  forces  before  it .(  8:  4  )  Without  outside
intervention  it seemed  inevitable that  the entire  Korean
peninsula would be  united under the communist  leader , Kim
Il Sung .
     Western military experts were stunned  by the NKPA . It
was  not what they had expected . The  American intelligence
network knew very little about North Korea or its military .
There was  no American intelligence  network in  North Korea
prior to the  war . ( 5: 13 )  In fact , prior to  25 June ,
America had  paid very  little attention  to North  Korea at
all. If they  had , it would have been frightening .
     The NKPA was a well  trained and modern force carefully
constructed  along  Soviet   lines .  For  over   two  years
hundreds  of  Soviet advisers  had  molded  the army  .  The
Russians had  also generously supplied  it with arms  . Each
NKPA division  , for  example , was  equipped with  12 122mm
howitzers , 24 76mm  guns , and 12 45mm antitank  guns . All
were recent World War II vintage . The Soviets also provided
the NKPA  with tanks  . Each  infantry division  had organic
tanks and  there was  also a  separate tank  division .  The
105th Armored Division  boasted 120  modern T-34 main battle
tanks  .( 9:  17  ) The  Chinese  also lent  a  hand .  They
released 16,000 Koreans  from their army to join  the NKPA .
The men   had fought for  the communists during  the Chinese
Civil War .  These battle hardened troops became the core of
the NKPA .
( 9: 18 )
     The ROK  forces were no match  for the North  Koreans .
The ROK  army was intended to  be only an  internal security
force . It was trained and equipped by the United States for
that  mission  .  They  had neither  the  weaponry  nor  the
training  to stand  up  to armored  forces  . Their  retreat
quickly dissolved into a  rout.
     World reaction to the invasion was surprisingly swift .
On 27  June , the  United Nations  called on its  members to
help  South  Korea   "  repel  the  attack  and  to  restore
international peace and security in the area  . " .( 2: 60 )
On the 7th  of July , with the North  Korean attack reaching
deep into South Korea , the United Nations approved a second
resolution authorizing the United States  to form a combined
military force  and appoint  a Supreme  Allied Commander  to
fight in Korea . On 8  July , President Truman named General
of the Army Douglas MacArthur as Commander in Chief , United
Nations Forces ( CINCUN ) . ( 8: 1 )
     Armed  with  the  UN resolution  ,  the  United  States
immediately rushed troops  to the aide of South  Korea . The
only  troops available  were those  on   occupation duty  in
Japan.  Pushed into  a   rapidly  deteriorating situation  ,
they proved to  be ill  trained and  mentally and physically
unprepared for  combat .  They were no  match for  the North
Koreans  . By  the middle of July the  United Nations forces
were  pushed  back  to  the   southern  end  of  the  Korean
peninsula.   As   the  troops   huddled  inside   the  Pusan
Perimeter, the war seemed lost.
     In August  , General  MacArthur in  a single  stroke of
strategic brilliance , turned the war around . His World War
II experience had shown him  the value of amphibious warfare
and the  indirect approach .  The Inchon  amphibious landing
routed  the North  Koreans .  This operation  , hundreds  of
miles to the  rear of the North Koreans ,   cut their supply
lines and forced their withdrawal . By the end of  September
the capital of  Seoul was liberated and the  border of South
Korea restored . MacArthur was hailed  as a hero . President
Truman and his administration were applauded for their stand
against communist aggression . The  conditions called for by
the original United Nations resolution  were satisfied . The
war should have been over . Unfortunately , success produced
greater expectations .
     The  United Nations  forces  launched  an invasion   of
North Korea . The intent of  the campaign was to destroy the
NKPA and unite  the peninsula under the  democratic auspices
of the South .  It  was one of the most   disastrous and ill
conceived campaigns in American military history .
     CINCUN's plan was simple . It envisioned a giant pincer
movement up  both sides  of North  Korea .  These pincers  ,
Eight Army on the west and X Corps on  the east , would meet
at the Yalu  River . This double envelopment  would trap the
remaining NKPA in  the mountainous terrain in  the center of
the country .  ( 10: 9 ) To support the maneuver , a massive
air interdiction effort would be made to isolate North Korea
from her  sources of  supply across the  Yalu in  Russia and
China .
     The plan ended  in disaster . The  attack was launched
in October  against a  disorganized and  fleeing enemy  . By
early December ,  the situation was entirely  reversed . The
United Nations  forces were in  full retreat with  four full
Chinese field armies  in  pursuit . Seoul fell  once again .
There would  be years  of tough ,  bloody combat  before the
Americans fought their way back to the 38th parallel .
     All campaign  plans are based  upon assumptions  . They
represent vital pieces of  missing information , predictions
of future  conditions or possible  third party  actions that
could  have a  crucial  effect upon  the  plan  .  The  high
command made several critical assumptions prior to
the fall/winter campaign of 1950 and those assumptions were
wrong : It was those faulty assumptions that assured defeat
in the cold  , icy hills of North Korea  . Those assumptions
were  contrary  to the indications contained  in operational
and intelligence  reports .   Only General  MacArthur really
accepted  them , but his opinion was sufficient . His impact
was such that   despite their misgivings , some  of the best
minds in  the American government  and military  approved in
his plan .   By  this point in the war ,  as General Matthew
Ridgeway pointed out :
          Even his superiors ,it seemed ,began to doubt
          if they should question any of MacArthur's
          decisions and as a result he was deprived of
          the advantage of forthright and  informed
          criticism , such as every commander should
          have ... ( 1: 232 )
     General MacArthur   made four basic assumptions  in the
fall of 1950 . They were  : (1) The Chinese Communists would
not enter  the  war ; (2) The North Korean People's Army was
finished  as a  fighting  force ;   (3)  The  caliber of  the
average   United  States  fighting  unit   had  dramatically
improved since  the start of  the war  ; and (4)  Only total
victory was an acceptable conclusion . Each was wrong .
     MacArthur was America's expert on  the oriental psyche.
He believed that , as did most people inside and outside the
United  States government  . This  belief was  based upon  a
rather  superficial look  at his career  . He  had spent the
majority of his  time in the Far  East , but mainly  in  the
Phillipines .  His victories  over the  Japanese during  the
Second  World  War and  his  handling  of  them  during  the
occupation  were  magnificent  .   These  accomplishments  ,
however , did not  make him an expert on the  Chinese .  His
dealings with the  Chinese were exclusively with  Chiang Kai
Shek and  the Nationalists  . He  had never  dealt with  the
Chinese Communists , did not know  their leaders , yet would
constantly insist   that he  could accurately  predict their
behavior . ( 2: 66 )
     The   Chinese   never  attempted   to   conceal   their
intentions.  Author  William  Hopkins   took  part  in   the
campaign  near the  Chosin  Reservoir  . A  Marine  infantry
officer  , he  commented  that "  no  commander in  American
history had received  more warnings of impending  disaster ,
yet  failed to  heed those  warnings than  had MacArthur  in
North Korea . ".  ( 4: 13 ) That quote  should have included
both MacArthur  and the  American government  . The  Chinese
were  careful  to  issue warnings  both  diplomatically  and
     The Chinese  political leadership made the  decision to
prepare  for war  in  Korea in  midsummer  of  1950 .  Their
decision was based on the assumption  that the NKPA had over
extended  itself logistically  during  its  campaign in  the
south. The   Chinese leaders  were sure  that the  Americans
would successfully counterattack and the North Koreans would
have  to retreat.  General Peng  Dehuai ,  the Commander  in
Chief of the Chinese forces in Manchuria , told his staff in
September   "  My  instructions  are  to  intervene  if  the
Americans cross into  the Democratic Peoples Republic    ". (
9: 78 )
     The  Chinese  strength  in  Manchuria  climbed  as  the
Americans approached the 38th parallel  . In July , American
intelligence estimated their strength at  about 115,000 . By
the end  of  August that had  increased to 246,000  . By mid
September  there  were  reports of  450,000  Chinese  troops
massed in Manchuria . ( 8: 9)
     In    September  ,   Chinese   warnings  about    their
intentions came from  numerous sources . In New  Delhi , the
Indian  Foreign Minister  informed  the American  ambassador
that if the Americans crossed the   38th parallel in Korea ,
China would  enter the war .  The British ambassador  to the
United States  told the  State Department  that he  had seen
messages between the Chinese leaders  and President Nehru of
India , indicating the Chinese willingness to fight if North
Korea  was  invaded  . The  American  ambassador  to  Russia
received  the  same  warning  from  the  Dutch  and  British
ambassadors in Moscow .  ( 5: 198 )
     On  the 27th of September  , American airplanes strayed
over  the Yalu  River  and attacked  a  Chinese airfield  in
Manchuria .  The American  Government immediately  issued an
apology  ;  however  the  Chinese  Government  regarded  the
incident as a true indication of American intent . ( 5: 226)
     The Chinese became more specific  in their warnings to
the United States in  October . On the 3rd of  October , the
Chinese Foreign Minister  , Chou En-lai summoned  the Indian
ambassador to his office . Chou  warned Mr. Panikkar that if
American  or other  United Nation  troops   crossed the  38th
parallel the Chinese  would  be compelled    to  come to  the
North's defense.  If only   South  Korean troops  entered the
North then China  would not get involved .  This message  was
relayed to Washington within 24 hours . ( 5: 211 )
     General MacArthur  was told  about the  various Chinese
warnings but  his strategy remained unchanged.  He continued
to  assure  everyone that  the  Chinese  would not  dare  to
intervene in Korea  . On 7 October the  first American units
began to probe into North Korea  . The probes quickly became
a general advance .
     On  the 9th  of  October, Chou  En  lai issued  another
warning . " The American War of Invasion in Korea has been a
serious  menace  to the  security  of  China from  its  very
start." . ( 5: 215 )
     President Truman  and General  MacArthur  met  on Wake
Island in the Pacific on the 15th of October . The President
wanted to hear  the general's  opinion of the Chinese threat
in person.  General MacArthur reassured the  President that,
in his opinion  , the Chinese would  not enter the war  . In
fact, one  day earlier  General Peng's  troops had  begun to
cross the Yalu . ( 9: 117 )
     The 25th of October brought a remarkable event . South
Korean troops reported capturing Chinese  prisoners . By the
end of  the month  , 55 Chinese  prisoners were  in American
hands . Each  talked quite candidly about  a massive Chinese
crossing of the Yalu River . ( 9: 160 )
     Early  November  brought more  ominous  developments  .
American  pilots returning  from missions  over North  Korea
reported  seeing  masses  of  Chinese  troops  and  vehicles
crossing the Yalu River bridges . ( 6: 70 )
     The evidence had become too overwhelming to ignore . By
the 6th  of November CINCUN  Headquarters in Tokyo  began to
speak of  limited and low  level Chinese involvement  in the
war . Although the most  critical assumption of the strategy
had  been radically  altered ,  the  campaign plan  remained
unchanged .
     The  second pillar  of the  campaign  strategy was  the
assumption that  the NKPA  had been  destroyed as   a viable
fighting force .  There was no doubt that they  were in full
retreat ,  but they still  retained a dangerous  capacity to
resist .
     The  counterstroke at  Inchon  was  brilliant but  also
lucky .  The Seoul  / Inchon  area was  lightly defended  by
second rate troops . All of  North Korea's front line troops
and their strategic reserve had  been pushed south for their
culminating  attack  against  the   Pusan  Perimeter  .  The
American counterattack  struck directly into  a gap  held by
weak ,  rear area units . ( 9: 96 )
     The Chinese  assumption about  the North  Korean attack
had been correct  . The North Korean advance  had outrun its
supply lines  .  Their  supply system  was never  any better
than  primitive   and  it   collapsed  under   the  American
counterattack . Exhausted by the  effort of their successful
attack  , their  supply lines  cut  and in  danger of  being
caught  between two  American  forces  , the  North  Koreans
retreated .  The Americans superior mobility   and firepower
and the  NKPA's lack of supplies  turned the retreat  into a
rout . The North Koreans raced  north counting on the rugged
terrain , coming winter and possible Chinese support to save
them . General MacArthur's frequent calls for surrender went
unanswered .
     On  October 20th  General  MacArthur's Headquarters  in
Tokyo issued this statement :
             Organized resistance on any large scale
             has ceased to be an enemy capability .
             Indications are that the North Korean
             military and political headquarters may
             have fled to Manchuria . ( 2: 124 )
     This declaration was premature . Two months later " The
most evident  troops ( attacking  the Americans ) were North
Koreans  , who  seemed  to have  regained  their morale  and
strength ." . ( 6: 198 )
     The third assumption  was closely tied to  the second .
The  rapid  North  Korean collapse  convinced  the  American
commanders  that   they  had   achieved  superiority  at  the
tactical  level .  They  were  convinced that  the   American
forces  had overcome  the peacetime  mentality  and lack  of
training  responsible  for  their  initial  defeats  .  This
assumption was also wrong .
     The  brunt   of  the  difficult  fighting   during  the
counterattacks  was  borne  by  selected  American  units  .
General MacArthur  said that the  Inchon operation  was only
possible " . .. if I had the First Marine Division..." . ( 1:
185 ) He knew that the troops currently in Korea were not up
to the  task . The Inchon  / Seoul operation was  mainly the
work  of the  First  Marine Division  and  the 7th  Infantry
Division . The remainder of the American forces was involved
in  pursuit  operations  that  summer  and  fall  against  a
disorganized and retreating  enemy . The rapid  advance back
to  the  38th   parallel  was  not  a   true  indication  of
improvement among the American troops . This became only too
evident when they were subjected to  the Chinese attacks . A
private in the  8th Cavalry spoke of his  unit's reaction to
being attacked by the Chinese :
             There was just hysteria on the position.
             It was everyman for himself.... In the
             end, I just  ran with the crowd . We just
             ran and ran until the bugles grew fainter.
             ( 2: 128 )
     The disintegration  of the  NKPA produced  a degree  of
arrogance  by  the  Americans  .   The  early  North  Korean
victories  had  been  shocking  ,  but  now  the  slumbering
American giant was aroused . The American  High Command were
all veterans  of World War II  . They seem to  recognize the
scenario .  There would  be three phases.  .Phase one  was a
blinding sneak  attack by  crafty orientals  that failed  to
deliver  a  knockout  punch  . Phase  two  was  a  slow  and
disappointing  American response  .  Those  two phases  were
behind  them  .  Now  came  phase  three  ;   a  devastating
counteroffensive that culminated in total victory.
     The  American  distain  for   the   capability  of  the
oriental soldier was evident  even after the Chinese entered
the war  . On November 28th  the American lines  reeled from
massive Chinese  attacks . Lieutenant  General Almond  , the
Commander of  the X  Corps , addressed  the members  of task
Force  Faith ,  an  army unit  rushed  forward  to stem  the
attacks :
             We're still attacking and we're still going
             all the way to the Yalu . Don't let a bunch
             of chinese laundrymen stop you . ( 2: 154 )
Within twentyfour hours  Task Force Faith was  destroyed and
its commanding officer dead . These laundrymen could fight .
     America  had convinced  itself that  total victory  was
possible .  The fourth fatal  assumption was that the entire
peninsula could be liberated from communism.
     In  1950    ,   President  Truman  and   his  Democratic
Administration were being  blamed  in the United  States for
the worldwide spread of communism and  , in particular , the
loss of China  . Now Truman saw an opportunity  to roll back
overt communist  aggression and actually eliminate  a soviet
client state  . On 1  September , President  Truman approved
and issued a National Security Council Study ( NSC 81 ) that
declared  that all  Koreans "  had the  right to  be free  ,
independent and  united" and directed  the United  States to
work toward that goal . ( 1: 236 )
     The  Joint  Chiefs  of  Staff   issued  a  new  mission
statement to General MacArthur on the 27th of September:
            Your military objective is the destruction of
            the North Korean armed forces . In attaining
            this objective you are authorized to conduct
            military operations ... north of the 38th
            Parallel in Korea ... as a matter of policy,
            no non-Korean ground forces will be used in
            the northeast provinces bordering the Soviet
            Union or in the area along the  Manchurian
            border . ( 1: 237 )
     On the 29th of September the new Secretary of Defense ,
George C. Marshall sent  personal guidance to MacArthur." We
want you to feel unhampered  tactically and strategically to
proceed north of the 38th Parallel .".( 1: 237 )
    MacArthur certainly felt unhampered . He declared that
" This  so  called  buffer  zone  ...  would  bankrupt  our
political , military  and psychological position in  the Far
East . " . ( 6: 72 )  He never really paid attention to it .
On the 24th of November Lt  General  Almond flew to the very
border  of China  and  gazed across  the  Yalu  . The  press
cameras captured the moment for the world .
     General MacArthur made his intentions perfectly clear .
The day before his forces commenced  their final push to the
Yalu he published this proclamation:
          If successful ,  this should for all practical
          purposes end the war , restore peace and unity
          to Korea , enable the prompt withdrawal of the
          United Nations military forces , and permit the
          complete assumption by the Korean people and
          nation of full sovereignty and international
          equality . It is that for which we fight . ( 6:
     The reasons  for the defeat  of the American  forces in
North Korea in  1950 are still debated . After  the war, all
of  the major  American participants  published reasons  why
they were  not to blame . All  of them saw the defeat caused
by reasons beyond their span of control .
     There is  no doubt that  some factors were  beyond the
American span  of control  . Certainly  the weather  of that
Korean winter had  an impact on the  campaign . Temperatures
dropped to record lows and both sides suffered horribly from
frostbite . The   rough ,mountainous terrain of  North Korea
also played a part  in the defeat . The Marines  , however ,
overcame these obstacles during the Chosin Reservoir battles
and  were victorious  . These factors were  not the  crucial
ones .
       America's allies maintained their support of the war .
The United  States was not left  alone to fight  during this
part  of the  war .  The British  , the  Turks and  numerous
other  allied armies  fought along  side  the Americans  and
South Koreans during the fall and winter of 1950 .
       The  campaign failed  because  the  foundation of  its
planning was based on hope rather than reality. In order for
the plan to  be successful the assumptions behind  it had to
be realistic predictions  of future conditions .  These were
not . The  Americans planned assuming the best  and the plan
fell to pieces.
       It  is  clear that  the  key  assumption was  the  one
concerning the  Chinese entry  into the  war .   The Chinese
intentions were  so clear  and their impact  on the  plan so
enormous that it is difficult to understand how the planners
could have dismissed them so easily .
     The power of the MacArthur personality certainly played
a  major part  in  the acceptance  of  the assumptions.  His
impact may  have been  overstated, however  . The  President
,the Secretary  of Defense and the Joint Chiefs of Staff all
had a  clear picture of the  Chinese intentions and  had the
authority to  disapprove the plan  . Each  expressed concern
with the  plan but deferred to the commander on the ground .
     Certainly  CINCUN's  staff and  subordinate  commanders
share responsibility for the fiasco . Each of them was aware
of the weaknesses of the plan  . Most of them were convinced
that the  Chinese would intervene  eventually , yet  none of
them chose to challenge MacArthur .It is the  responsibility
of staff officers and subordinate commanders to ensure plans
correlate capabilities with goals.
            Telling a superior officer that he is
            wrong is an act that requires enormous
            moral courage ( "laying your commission
            on the line " was the phase
            General George Marshall ). But a good
            officer does so ... when he feels a
            serious mistake is about to be made,
            and lives lost as a result. ( 1: 232)
      In the  end there  is a  simple lesson  in all  this .
Military planners  must assume the  worst .  Military  plans
can't be based on  what we hope is true, but  rather must be
based on what we  hope isn't true . The cost  is too high to
do otherwise
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