HIGHLAND HEIGHTS, Ky., Feb. 1— As the role of black soldiers is documented in the history of World War II, J. Robert Lilly is trying to fathom one more distinction of that American fighting man: the fact that almost four times as many black soldiers as whites were executed in Europe after military courts-martial, even though blacks made up less than 10 percent of the troops.
"This needs to be sorted out and made right," Professor Lilly said in a recent interview at Northern Kentucky University, where he teaches sociology and criminology. The professor, who is white, stumbled on to what he suspects is a little-known chapter of American racism in doing research in England on prison punishment.
First, he heard about Albert Pierrepoint, England's official hangman during the war, and some of the hangings he carried out for the American Army at Shepton Mallet prison near Somerset. American soldiers were executed at the prison for the murder and rape of English civilians.
This set Professor Lilly looking for official records. Eventually, with the help of Frederick M. Kaiser, a senior research associate at the Congressional Research Service, he uncovered a 1946 summary of court-martial discipline dispensed in the war's European theater. In this he found enough racial data to bolster what he had picked up anecdotally in England: Black soldiers paid for capital crimes disproportionately at the gallows in the segregated military of that time. 55 Blacks Executed
With black history month being celebrated around the nation, Professor Lilly is intent on getting all the details of the executions and spreading the information. The professor, rich with curiosity but short on money, is planning to write a book about these military executions.
By his accounting, 70 soldiers were executed after courts-martial in Europe during the war, 55 of them black and 15 white. About 70 more executions were carried out elsewhere in the American military, but so far no breakdown on racial data has been obtained. "It was very clear that blacks were being punished in almost all instances a hell of a lot more for their behavior, proportionate to their presence, than the white soldiers were," Professor Lilly said.
"There's no question that in most instances the crimes committed were horrendous," he said. "But we don't know whether whites got away with the same acts, particularly the rapes."
The military data he has gathered in Europe show that blacks (or "colored," as the military referred to them then) made up 79 percent of the soldiers executed in Europe, as against 21 percent for whites. Death Sentences for Rape
The rate of execution for black soldiers was even higher for the rape of civilians, for which 25 blacks (87 percent) and 4 whites (13 percent) were put to death. In 28 murder convictions, 22 blacks and 6 whites were executed. Of the 12 executed for murder and rape, 8 were black and 4 were white. The other execution was that of Eddie Slovik, a white, for desertion. The United States Army Center of Military History in Washington says very little information is available on the subject. But one historian there, Russell J. Parkinson, was able to confirm the basic data that Mr. Lilly is using. "There's clearly a black preponderance," Mr. Parkinson said, after reviewing the execution records and finding Mr. Lilly's quest a worthy avenue for scholarship.
There were about 700,000 black soldiers in the United States forces in World War II out of a total of more than 10 million men and women who served. Mr. Lilly said about 160,000 black soldiers passed through England to the European theater, compared with several million whites. Finds Clues of Racism
Professor Lilly said the executions of blacks for the rape of English civilians strongly support his suspicions of a Jim Crow sort of racism in American military justice in World War II.
"I was hooked on the subject," he said. "I found no one has written anything about it. Nobody knew anything."
For less serious, less interracially explosive offenses, like barracks dishonesty and drunkenness, Mr. Lilly found the races represented proportionally. White soldiers were charged 9 times out of 10.
But sex offenses registered differently, even apart from outright rape. Black soldiers made up more than 40 percent of the total accused of sex crimes, and they were convicted in two-thirds of the cases; white soldiers were convicted at a 40 percent rate.
Professor Lilly said racism seemed to be suggested as well in the broader military trial record in Europe. He found a total of 36,102 courts-martial for offenses ranging from absence without leave to assault. In these cases, blacks were the accused 22 percent of the time, more than twice their proportionate number in the ranks and three times the number when violent crimes were involved, he said.
In particular, Professor Lilly is intent on getting all the details of the 19 soldiers who were put to death in England, two by gunfire, the rest by hanging. The Army eventually hired Mr. Pierrepoint for this because of his skill with the noose.
"A perspective is lacking, and until we find it out we'll keep perpetuating the same social experiences," Mr. Lilly said. The nation must reach back for the sort of history told in the black-white executions, he said, "to bring the Los Angeles riots and other problems into stark relief." Segregated American Army
Black soldiers were segregated from whites in the Army as troops were massed in England for the cross-channel invasion of Europe in 1944. With few exceptions, all the officers were white.
Most important, one pillar of military justice was the overriding discretion of commanding officers. They had a patriarchal-like power to decide whether to bring a court-martial and appointed the officers to take part. Commanders could also transfer troublesome soldiers as a resolution to a problem, and potential witnesses could be made to feel career-threatening pressures.
At least some of the rape cases, Professor Lilly suspects, were rooted in white soldiers' resentment over interracial dating, and that eventually overtook an initial spirit of English welcome extended to black soldiers. He found one rape conviction where the purported victim's white boyfriend, not the woman herself, had testified.
In another case, he said, an entire company of 200 black soldiers was summoned to attention in the barracks square so that a victim could review them and, finally, accuse one of rape. Help From Columbia Professor
The commanding officer's great power of discretion is what most concerns Christo Lassiter, a professor in the College of Law at the University of Cincinnati and a former marine who specialized in courts-martial and who is now assisting Professor Lilly. He is seeking copies of the individual cases from Government archives to study the level of evidence and defense.
Professor Lassiter, who is black, said the search is relevant not only to black history but to the debate about the quality of military justice. He said a commander's discretion remains "the major problem," even after considerable progress in military justice has been made in the last 50 years.
"The reason we should care what happened in military justice in the 1940's is that Americans are still signing up for the military, and these questions remain about justice," Professor Lassiter said.
Photo: Prof. J. Robert Lilly, left, of Northern Kentucky University in Highland Heights, has stumbled on to what he suspects is a little-known chapter of American racism: that almost four times as many black soldiers as whites were executed in Europe after military courts-martial. At right is Christo Lassiter, a professor in the College of Law at the University of Cincinnati who is now helping Professor Lilly. (Mark Lyons for The New York Times)