CHAMPION: Joe Louis, Black Hero in White America. By Chris Mead. Scribners. 330 pp. $18.95. Creamer

WHEN JOE LOUIS began fighting professionally in 1934, three years before he won the heavyweight championship, there were almost no black athletes prominent in American sports. There were no blacks in major league baseball, none in pro football and only a few in college football. A handful of blacks played college basketball, but the professional game as we know it did not exist. A few blacks had won Olympic gold medals (not including Jesse Owens, whose Berlin Olympics were still in the future), but track and field remained predominantly white.

Even in boxing, blacks were not in great evidence. Since the introduction of the Marquis of Queensberry rules in the 1870s, there had been only one black heavyweight champion -- the controversial Jack Johnson. In the other weight divisions there had been more than 100 champions but only eight had been black, and late in 1934 there were none.

The paucity of blacks in sports reflected their place in American society. In the 1930s, infinitely more so than today, blacks were second-class citizens who were "kept in their place" by written and unwritten laws. Except in variations of the servant- master relationship, most blacks had little contact with whites, even with those who in a catchword of the day considered themselves "tolerant." In white-dominated society, there were no black teachers, no black nurses, no black bank tellers, no black store clerks, no black office workers, no black foremen. Even wealthy, educated blacks dealt primarily with other blacks, and highly visible blacks who achieved distinction in such fields as entertainment and the arts were treated as social inferiors in most levels of white society.

It is a major premise of Chris Mead's Champion: Joe Louis, Black Hero in White America that the unlettered, apolitical Louis, who by today's more militant standards was something of a Tom, changed all that -- or, to be more realistic, that his career was the trigger that ignited the civil rights movement.

Louis came into the corruption and mediocrity of boxing in the mid-'30s like a fresh breeze. The prestigious heavyweight crown had bumbled its way in five years from Max Schmeling to Jack Sharkey to Primo Carnera to Max Baer to Jimmy Braddock, fighters unable or unwilling to win consistently. Louis (whose career began by happy coincidence on the Fourth of July) entered this largely white world and in 18 months captured the imagination of America by winning 27 straight fights, 23 of them by knockouts. Before and after his stunning loss to Schmeling in June, 1936 -- one of the most startling upsets in boxing history -- he swept away the detritus of former champions by knocking out all five of his predecessors (Schmeling in the first round of their famous rematch in June, 1938). He defended his championship 19 times in the first four years after he won it and 25 times in all before he abdicated in 1948.

AMERICA LOVES a winner, and it particularly loves a gracious winner. Louis was that, time after time exhibiting toward defeated opponents his innate sense of decency. He was a gracious loser, too, on the rare occasions when that happened. Even his disastrous comeback, which ended when a youthful Rocky Marciano knocked him out, 17 years after Louis's first pro fight, did not dim the esteem in which he was held.

The onslaught of World War II added to his luster. He joined the army a month after Pearl Harbor and was hailed as a prime example of American unity and patriotism. Black Americans loved him because of the vicarious satisfaction he gave in standing up to and defeating the white man again and again (few of Louis' opponents were black), and white Americans put him on a pedestal. More than Paul Robeson, Marian Anderson, A. Philip Randolph, Louis came to represent the Negro in white eyes. The often lurid white press in the beginning had described Louis as though he were an animal that had dropped from a tree. (Grantland Rice, a renowned columnist of the day, called him "a bush master," "a brown cobra," and referred to him as having "the speed of the jungle, the instinctive speed of the wild.") Now it patronized him, overlooking his faults and dwelling on his dignity and his good deeds:

"There never has been a heavyweight champion who has behaved better," wrote the The Chicago Tribune. "There are those who say he isn't very bright, but he has had enough education and he is bright enough to know where his duty lies."

Some black intellectuals resented white America's choice of a boxer as the symbol of his race while ignoring those better able to voice black needs and wants and attitudes. But Mead argues thatccomplishments in the ring and his admired behavior out of it forced white America to look at the no longer invisible black man and to praise what it saw. If one black could command such recognition and respect from whites, then others could too. Ergo, the Federal Employment Practices Commission, Jackie Robinson, Brown vs. Board of Education, Rosa Parks, Dr. King, equal opportunity. The fight goes on, but, according to Mead, Louis got it going.

His account of Louis' career and personality draws heavily on earlier, livelier books about the fighter, but Mead's own research, notably a relentlessly detailed analysis of the racial bias in sports journalism 50 years ago, adds much to the story. And boxing aficionados will be fascinated by his punch-by-punch dissection of key rounds in several of Louis' fights, among them the two with Schmeling.

All in all, Louis was an exemplary figure, and it's good to have this new, expanded account of his life. It's a valuable addition to American social history.