IN 1788, ONE YEAR before the ratification of the U.S. Constitution and the official beginning of this nation, a tall, dignified African prince came to America in chains as a slave.

Abd Rahman Ibrahima had led a privileged life in the Moslem territory of Futa Jalon (now part of the Republic of Guinea) before being captured in battle.

But as he crossed the Atlantic in a dismal and crowded slave ship, the 26-year-old prince and professional soldier faced the prospect of a life of menial field labor on a farm outside Natchez, Miss. He was not the first - nor the last - African of royal birth to be plunged into slavery in the New World.

Arriving at the 1,000-acre Thomas Foster farm, Ibrahima, still wearing his long plaits and knowing no English, identified himself to his new owner and offered a ransom. He probably spoke through a Mandinka intermediary, who translated.

"Picture that extraordinary conversation," wrote historian Terry Alford. "A scorned Muslim endeavoring to explain to an incredulous and little-schooled farmer about a kingly fater whose generosity would pour gold if his son was returned. Thomas could have been no more skeptical if Ibrahima had expressed a desire to enter Harvard College and study for the ministry."

The prince's plea was rejected, and, with that, Foster pushed on to more urgent business - getting homespun trousers and a haircut for Ibrahima. However, he allowed the African to retain some vestige of royalty - he called him "Prince" and permitted him to practice his Islam religion.

It took years for Ibrahima, a proud and noble man, to settle into another way of life following the shock of being plucked out of Africa and thrown into a completely alien land 6,000 miles from home.

Not for 40 years would he see Africa again, and, even than, he would die before making it to his native country. He died in Liberia on his way home.

The remarkable saga of Ibrahima is recounted in full for the first time in "Prince Among Slaves," a recently published book by Alford, who says the telling of the prince's story required on his part "a nearly unique synthesis" of life in Africa and America at that time.

The America that Ibrahima saw on arrival must not have been totally impressive. New Orleans had a population of only 5,300 only about two-thirds the size of the prince's capital, Timbo. No whites spoke his language or knew his way of life (he had studied for five years at Timbuktu).

In his adjustment to slavery, he struggled violently to avoid things like having his tresses cut. Without his hair, he thought he was like a child.

Next he was introduced to the demeaning task of picking up cut tobacco leaves behind a field hand snipping the plants.

Within days Ibrahima had enough. He slipped out of his bed one evening and ran away into the night. But Mississippi was unknown territory. He knew of no place to go.

Ibrahima might have considered suicide, a path some slaves chose, writes Alford. But, says the historian, "the Qur'an (the Koran) makes clear that the gates of Paradise are shut to those who murder themselves. However unfair his fate seemed, Ibrahima felt his misfortune came from God."

So after severl weeks of wandering in the forest, he returned to the farm. He walked in on Sarah Foster, who was sitting alone, sewing.

Tattered garments hanging from his powerful frame, the prince prostrated himself before her.

Writes Alford: "Taking one of her feet in his hand, he liftd it up and put it down upon his neck . . . Ibrahima meant by it something his ignorance of English did not let him say. He was placing his life in the hands of the Fosters . . ."

Ibrahima fell into the farm routine, helping harvest the tobacco, cotton and rice crops. Six years after his arrival, the prince was married to Isabella, a newly-purchased woman who already had children.

Alford writes: "For Ibrahima the event was no ordinary milestone. It marked a coming to grips with his terrible life. His wife at Timbo had probably remarried; his son, just two years old when he left, could not even remember him . . . The early arrival of a child brought a still deeper involvement in his new world."

However, there were occasional - and painful - reminders of his previous life. Once he was recognized by a former subject. "Abdul Rahaman," the man cried out and then dropped his face to the ground.

Almost 20 years after he arrived in this country, Ibrahima was recognized by a white doctor who had known the prince and his father in Africa. Moved by the prince story of capture and bondage, John Coates Cox tried to buy Ibrahima's freedom. But Foster refused. Ibrahima had become too valuable a servant, his steadiest worker and a moral example to other slaves.

A pious man, Ibrahima did not curse or drink liquor and was never accused of a dishonest act, Alford found. He retained his strong belief in Islam, resisting all efforts to convert him to Christianity.

"I tell you," Ibrahima said to Cyrus Griffin, a lawyer, "the (New) Testament very good law; you (Christians) no follow it; you no pray often enough; you greedy after money. (If) you good man, you join the religion. (But) you want more land, more neegurs; you make neegur work hard, make more cotton. Where you find dat in your law?"

Life had dealt the prince an unfair hand.But he made the best of what he had. His family grew to five sons and four daughters. He gradually took on more responsibility at the farm and was allowed to grow and sell his own vegetables.

Because of his unusual background there were many whites interested in Ibrahima's case. they cultivated his friendship and tried to arrange for his freedom.

After 40 years, Foster relented and agreed to give Ibrahima his freedom. The year was 1828. John Quincy Adams was President and Henry Clay was secretary of state.

Andrew Marschalk, a transplanted New York newspaperman, and attorney Griffin, a transplanted sixth generation New Englander, had appealed about Ibrahima's freedom to Clay, who took the matter to the president.

Under the weight of federal pressure, Foster freed the prince. But the Slaveowner, according to the historian, never wrote the president - "he would only sign the manumission papers - and nothing else."

The government paid for Ibrahima's hip transportation. The American Colonization Society, a pricate organization trying to rid the United States of its black population by sending if back to Africa, handled the arrangements.

In an attempt to buy his children's freedom, Ibrahima toured Washington, Philadelphia and Boston on a subscription drive that netted about $3,500, enough to purchase two sons and several grandchildren. At least two sons remained in slavery in Mississippi and fathered families which Alford could not trace.

On Feb. 9, 1829, Ibrahima, his wife, children and grandchildren left for Liberia. They sailed on the Harriet. The ship's passenger list mostly included former slaves and free blacks who would help colonize the country.

The immigrants stepped from a harsh North American winter into a buoyant African spring. Passengers began dying from a powerfully infectious fever, fed by exposure, fatigue and disorganized living arrangements.

On July 6, 1829, nearly five months after returning to Africa, and only 300 miles from his home city, Ibrahima died from a raging fever.

Alford said the more than 40 years Ibrahima had spent in America hand chipped away at his personality and caused him to make many accommodations with racism. But he always clung to the God of his youth, "seeking to understand and accept what had befallen him."

Alford, 32, a history professor at Northen Virginia Community College, first heard of Ibrahima when he stumbled across a faded letter from Clay concerning the Moorish prince. The historian was than a 22-year-old graduate student at Mississippi State University.

"I was working in the county deed records, buried in giant cloth-bound volumes of laminated pages," Alford has written. "I had not heard of this particular individual before, although I knew that from time to time African princes and kings had wound up as slaves, so I wasn't surprised."

But Alford was caught unaware by the full report of Ibrahima's life he got the next day from a Natchez antiquarian. Like many Natchez citizens, Mary Postlethwaite knew of Ibrahima and gave Alford a general description of the African's life.

Intrigued, Alford researched the story at the university and found an account of Ibrahima's life published in the South Atlantic Quarterly in 1937 (he would later learn of three autobiographical accounts Ibrahima gave to people who knew him in his old age). The historian was fascinated. But it would be two years before he finished work on his doctorate and could turn full attention to this strange and shadowy historical figure.

"As I mused over the idea at that time, I realized I was dealing not only with an unusual story, but with a remarkable man as well," wrote Alford.

Alford's book resulted after seven years of research. In that time, the historian was employed for two years as a maintenance man, operated a copy machine and worked in a government typing pool.

To get the answer to why Ibrahima survived, Alford decided the Library of Congress was the best place to do his research. So he and his wife packed all their possessions in their car in May 1970, and moved to the District.

He worked on manuscripts of the American Colonization Society and later did not research in Mississippi (the Alfords spent their summers in their home state).

"One day I was looking through some old, dusty records and I turned to a page, and there were three black widow spiders," the historian recalls. "I jumped back! Some of those records hadn't been looked at for a hundred years.

"I uncovered a murder, several cases of wife abuse and desertion just by going through court records. The Fosters (owners of Ibrahima) didn't leave letters or diaries. So I had to rely on public records, newspapers and other letters.

"But some were very helpful. One of the Foster daughters-in-law filed divorce papers that told me a lot about family relationships, habits, even the way the house was decorated."

Alford's search led him to Dakar, Senegal, where he talked with Thierno Daillo, an authority on the history of Ibrahima's people, the Fulba. He also examined documents at the Institut Fondomental d'Afrique Noire.

But the historian wasn't allowed in Guinea because of the government's policy of not allowing Western social scientists to study there.

Alford also made trips to talk with scholars and work with material in Paris, London and Edinburgh.

Alford calls his book "my belated contribution to the civil rights movement." It may be modest of him to say that, however, for the historian and his wife worked in voter registration and the anti-poverty program in Sunflower County, Miss. They also helped rebuild black churches blown up by the Ku Klux Klan.

"I really, really wanted to get at the African personality in this book," he says. "I wanted to look at what they came from and what they experienced. We don't know the nature of the African immigrant to this country."

Alford writes: "Most of the men and women I teach today don't even remember L.B.J. But, at least, Ibrahima is out of time's shadow."