THE FORGOTTEN WAR America in Korea, 1950-1953 By Clay Blair Times Books. 1,136 pp. $29.95

CLAY BLAIR's superb history of the Korean War should swiftly go a long way toward making its title obsolete. It is far and away the most authoritative and comprehensive one-volume military history of the war, and it is a rattling good narrative as well.

It is, however, decidedly a military history. While Blair reminds us of the major reasons why the Korean War ought not to be forgotten, especially its reversal of the post-1945 American demobilization to transform the United States into a permanently well-armed nation, his main concern is with the conduct of the fighting and its implications about the nature of the American military system and possibly about the effectiveness of American armed forces in wars to come. Particularly he is concerned with the United States Army, which contributed 86 percent of American infantry manpower to the war, compared with 14 percent for the Marine Corps, and suffered an exactly proportionate share -- 86 percent -- of the American casualties. Blair tries to give 86 percent of his space to Army infantry operations.

In emphasizing the Army, Blair is especially concerned with the quality of Army leadership, particularly with the quality of the officers produced by the United States Military Academy who then provided, as to a large extent they still do, the critical nucleus of the officer corps. The book is rich in biographical sketches of Army leaders from the top down through battalion and even company levels, a richness that enlivens the text with human interest and also contributes much to Blair's assessment of the Army in Korea. While Blair finds a West Point education and the tactical doctrine that sprang from it generally sound, he also points to widespread weaknesses, notably in lack of preparation for leadership under adversity and still more in the retention of officers lacking enough physical vigor to lead effectively in the hardships of combat. Mountainous Korea imposed a special but obviously not unique demand for physical fitness, and the lack of it was a principal cause for the considerable housecleaning that had to be done in the midst of combat before the Army's leadership measured up with reasonable consistency.

Blair's favorite officers are thus mainly youthful, middle-grade, hands-on battle commanders such as Lieutenant Colonel John H. "Mike" Michaelis, a hero of the defense of the Pusan Perimeter as commanding officer of the combat team built around the "Wolfhounds" of his 27th Infantry Regiment, and Lieutenant Colonel John T. Corley, who reorganized the 3rd Battalion of the black 24th Infantry Regiment and then, receiving like Michaelis a battlefield promotion to full colonel, performed outstandingly in the difficult job of commanding the entire regiment during the troubled last days of a segregated Army.

Blair is less impressed with the abilities of higher-level commanders, with the inevitable exception of General Matthew B. Ridgway, whose place as one of the great soldiers of American history the book helps confirm. Especially low marks go to General of the Army Douglas MacArthur, whose one signal success in Korea, the Inchon landing, Blair rightly implies was more fortunate than it deserved, and whose generalship was otherwise continually guided by unrealistic perceptions leading to grave errors of judgment that MacArthur tried to conceal through less than honest reporting. But MacArthur's adversary, President Harry S. Truman, also emerges with tarnished laurels, particularly for bearing the principal responsibility for the Army's unreadiness to fight the war.

Blair's one set of judgments with which this reviewer is most inclined to take issue concern the commanding general of the Eighth United States Army in Korea from the beginning of the war until his death in a road accident on December 23, 1950, General Walton H. Walker. Because Blair devote his space mainly to the first year of the war, the phase of mobile conflict, Walker is a central figure through much of the book. Certainly Blair is right in describing Walker's generalship as of mixed quality; Walker surely made mistakes, including an overly hasty and reckless deployment at the outset and the overriding error that shaped the latter and most of Walker's other missteps, his refusal to resist the fanciful demands of MacArthur. But Walker may well merit a higher overall rating than Blair concedes to him, notably for the defense of the Pusan Perimeter. Blair acknowledges that Walker made good use of the mobility of the American forces to shift troops from one critical point to another, but he offers less praise than he might for the deftness with which Walker shuffled his most reliable units as fire brigades -- a display of tactical dexterity rarely paralleled in American military history, and no less commendable if the absence of parallels owes much to the infrequency of adversity in our military annals.

AMONG the units Walker had to juggle during the defense of the Pusan Perimeter was the black 24th Infantry, already mentioned in connection with the able Colonel Corley. Another of Blair's principal themes is the vexed question of the quality of the combat performance of black units, whose allegedly poor showing led directly to the October 1951 decision to desegregate the Army. Blair treads with extreme caution into what has become a battleground between black activists and apologists for the segregated Army when he turns periodically to discussing the accuracy of criticisms of black troops. His caution deters him from offering clear conclusions, but nevertheless he makes it altogether evident that in the most frequent focus of controversy, the 24th Regimental Combat Team, in fact gave the United States Army its first sizable victory in Korea, the capture of Yechon on July 21, 1950, and that the subsequent black combat record in Korea deserves considerably more praise than it has hitherto received.

Altogether, The Forgotten War is military history at its best, with all the narrative virtues that have made the military genre a favorite among nonacademic readers of history, and with much stimulus for serious reflection besides. :: Russell F. Weigley, Distinguished University Professor at Temple University and the author of "Eisenhower's Lieutenants: The Campaign of France and Germany, 1944-1945," is writing a history of modern warfare.