There was little mystery to the life of Thomas Henry French. Born in Baltimore, educated at Georgetown, he served with distinction but without fame in the Civil War and on the western frontier. After being court-martialed for drunkenness, losing his horse and dallying with two laundresses, he died at the age of 39, an incurable alcoholic, in Fort Leavenworth, Kan.

In death, however, the late and largely unlamented cavalryman became an enigma to the legions of military buffs who devote their lives to the esoterica of history. For Thomas H. French, who served as an officer under Gen. George Armstrong Custer, was the only member of that ill-fated regiment of Indian fighters whose remains could not be found.

And for the pre-eminent purveyor of Custeriana, a plump, puckish man named John M. Carroll, the elusive Thomas French became an obsession. Carroll, 51, has files on 300 of the men who served under Custer at the Little Bighorn, and no file is considered complete without a photograph of the grave marker.

Near desperation after years of searching, Carroll turned to The Washington Post for help. The renewed search began last week in Bryan, Tex., a steamy college town where Carroll devotes full time to his Custer mania. It ended Tuesday on a windswept hill high above Washington, where French's tombstone sits in Holy Rood Cemetery near the Georgetown Safeway store.

Carroll shares the same birthday with French and traces his own 7th Cavalry roots to his father, a member of the regiment, who taught military science at Texas A&M.

"I was born in the tradition of the yellow," said Carroll, referring to the traditional cavalry color. He is an unabashed booster of the controversial Custer and, like all serious Custer fans, has walked the Montana battlefield several times and visited Custer's Ohio birthplace, Michigan family farm, and Austin, Tex., Reconstruction headquarters. His auto license tag says "AUTIE," Custer's nickname. "Some guy in El Paso beat me to CUSTER," he said.

The final resting places of the 500 some men who died with the general or either fell or survived with two other battalions under his command hold special fascination for Carroll and other Custer devotees. They are always commemorating the dead, finding and refinding their graves, and where markers are either lacking or inadequate, seeking new ones from the U.S. government while organizing appropriate ceremonies.

The 215 who fell with Custer were hastily buried three days after the June 25, 1876 battle on the Little Bighorn and reburied with more ceremony a year later. Custer himself was exhumed from the site and reinterred at West Point with full honors in 1977, a year after the centennial. But the bodies of the rest of the regiment, who retreated with Maj. Marcus A. Reno or Capt. Frederick W. Benteen, lie scattered across the country, often in unhallowed, forgotten graves.

In the effort to locate them all, there are few more zealous than Carroll, co-author of the monumental work, "Roll Call on the Little Bighorn" and author of more than 50 other books and pamphlets, many printed at his own expense.

"It's very important that everything should fit into a pigeonhole and have a closed door eventually," he said in his small frame house, a virtual Custer shrine, containing the general's field glasses, bowtie and even a lock of his hair.

In the last two years, Carroll had found the graves of Sgts. Stanislaus Roy and Frederick Deetline, both Medal of Honor winners at the Little Bighorn, and was instrumental, in obtaining new headstones for them. He also located the graves of 23 enlisted men in Washington, in the old Soldiers Home National Cemetery.

But to his unending consternation, Carroll could not find the gravesite of Thomas Henry French. Not even an article in "The Cemeterian," a cemetery trade publication, had produced results.

The subject of the search was born on March 5, 1843, and baptized in Baltimore's St. Paul the Apostle Church. Little is known about his parents, but records show that French was reared by his uncle, Lt. Col. Martin Burke, who entered the Army in Washington in 1820 and fought in the Seminole and Mexican wars.

At age 10, French entered Georgetown College, a preparatory school, and records indicate, was a "day scholar" who lived at home and spent a total of $16.57 on books between 1853 and 1857. His first job was as a clerk in the diplomatic bureau of the State Department, where, coworkers later noted, his "deportment was uniformly correct" and "the duties assigned him were diligently and faithfully discharged."

In January 1864, young French enlisted in the Union cause as a private in the 10th Infantry, and aided perhaps by several letters his uncle wrote on his behalf, was commissioned a second lieutenant in May.

For "gallant services" at the Weldon Railroad encounter in August 1864, French received a battlefield commission as captain. For him, however, the war ended in October when he was wounded near Petersburg, Va.

After recuperating, he was stationed for a while at Fort Lafayette in New York harbor with his uncle and then went to Fort Ripley, Minn.

French was described by one colonel bidding for his services in 1870 as "young, energetic, temperate." Finally, in 1871, the brown-haired, hazel-eyed officer won assignment to Custer's 7th Cavalry at Fort Lincoln, N.D., where French posed for a cabinet card, a slightly stout but still dashing figure leaning on a saber.

As a member of Custer's command, French set out in the spring of 1876 to tame the fiercely independent Sioux. The 7th was to be part of a pincer movement and Custer's orders were to prevent the Indians' escape from another regiment's attack.

Instead, Custer led several companies to certain death when he chose to charge the Sioux encampment of some 4,000 warriors. Custer had divided the regiment into three battalions, however, and French commanded M Troop under Maj. Marcus A. Reno. Reno's forces engaged the Indians four miles east of Custer's "last stand" and then fell into disorderly retreat.

In an otherwise disastrous day for the cavalry, French's heroics stood out. "He was the first officer to get his company out on the line of skirmishers," a comrade recalled, and the Indians later singled him out as a most praiseworthy foe. When nominations for medals were solicited after the battle, French is said to have responded, "All or none."

French fought the Nez Perces the following year and was wounded at Canon Creek, Mont. For Thomas French after that, there was no more glory.

Like many soldiers serving long, lonesome tours of duty on the desolate frontier, French took to drink. An Army surgeon found him in December 1878, to have been "indulging in excessive drinking for three months . . . incurable by ordinary methods of treatment."

The after-effects of alcohol caused French to miss several days of his own court-martial in January 1879. After 17 days of trial, French was ordered severed from the service. President Rutherford B. Hayes commuted the sentence to "suspension from rank on half-pay for one year."

Before the year was over, French plaintively asked to return to his "station" because "his interests were all there" and "he had no other home." Instead, he was involuntarily retired from the service in March 1880.

"I hate to leave active service," he wrote a woman in Chicago three months later, "as I would like one more chance at those Sioux . . . I want revenge for my friends."

Thomas French died at the Planter's Hotel in Leavenworth less than two years later, on March 27, 1882, reportedly of apoplexy. He was buried at Fort Leavenworth National Cemetery, but on March 4, 1891, according to camp records, was "removed to Washington, D.C."

To John Carroll, French was a courageous and unheralded officer whose court-martial was an injustice, a misuse of military justice to settle "real, petty, imaginary and provoked problems and disputes." And Carroll set out to find his grave.

He was not the first. The National Archives show that a Washington law firm tried to find French's whereabouts in 1911 without success. "Inquiry among older clerks of the department failed to reveal any information," the government replied.

A letter from one former comrade to another the same year reported that French's "sisters had his remains removed to the East, probably to Arlington." But they weren't in Arlington or any other national cemetery -- although Romaldo Lucero, superintendent of the Soldiers Home cemetery, turned up a Thomas Holland French in San Francisco.

Carroll combed the National Archives here in December, with no luck. He also wrote the Archdiocese of Baltimore, the Veterans Administration, the Army Department, and Cleo A. Warren, a member of the Daughters of the American Revolution, who called the D.C. Bureau of Vital Statistics, only to learn that burial permits are destroyed after five years.

Almost as a last resort, he wrote to The Post, providing what leads he had to this reporter. Brian Pohanka, a Time-Life Books researcher who lives in Alexandria, Carroll said, had found the grave of William Van Wyck Reily, a Washingtonian who died with Custer, and might be able to help.

But Pohanka could lead a reporter only to Reily's grave in Northeast Washington's Mount Olivet Cemetery.

Kenneth Hammer, a Wisconsin econom ics professor and author of the seminal "Little Bighorn Biographies," provided details of Martin Burke, French's uncle and adopted father. The reporter wondered if French could be buried alongside Burke, and spent a day at the National Archives and on the phone. But it was a dead end. Burke was buried in Brooklyn, N.Y.

The parish records for seven old Catholic cemeteries are kept at Mount Olivet. They yielded no Thomas French, only an Elizabeth French who died May 18, 1873, aged 85. The Mount Olivet official, whose name happened to be Samuel French, suggested that Holy Rood Cemetery might be worth a check.

The records for Holy Rood, formerly a private cemetery and now owned and maintained by Georgetown University, are stored in a cardboard box in the basement of Harbin Hall. They showed a cemetery plot purchased for $37.50 on May 13, 1880, by Adele B. French, of Tenleytown Road.

And there, in Lot 257, Section 23, south half, were buried John, Bridget and Mary Burke, Mary Marshall, Rebecca and Adele Harry and Mary E., Adele B., and Ellen French, and Capt. Thomas H. French.

The next morning, his fifth day on the French mission, the reporter drove to the cemetery in eager anticipation. The tall stone monument with "FRENCH" inscribed at its base commands a stunning view of the District of Columbia and beyond. French's name is etched in front, with the words, "CAPT, U.S. ARMY RETIRED.

The moment of triumph was a solitary one. The cemetery was deserted.

"Oh, that's wonderful," said John Carroll from Texas. "I wish I could've been there with you," he sighed. "We become so wrapped up in it, they become like members of our own family."

The cemetery records led the reporter that night to the River Road home of John B. Harry II, 51, an electrical engineer and the great-great grandnephew of Thomas Henry French. Framed above the piano in the house near Tenley Circle is the Civil War commission of 2nd Lt. French.

Before the reporter left, the telephone rang. It was John Carroll, calling to ask the newly discovered descendant to formally request the reversal of Thomas French's court-martial conviction. Harry said he'd think about it. "I have to consult my aunts and uncles on that," he said.