"With the training they got, it was only normal that they won," said a young black French Foreign Legion recruit talking about his comrades-in-arms fighting in Zaire.

He had just finished an up-and-downhill obstacle course here at the Legion's boot camp in southern France in 2 minutes, 15 seconds - just two seconds under the time of his platoon chief, a French lieutenant.

Col. Raoul Forcin, the stockily built commander of the Legion training regiment, spoke with pride of the Zaire operation. "You see the training we give is good."

Until 18 months ago, when the training camp was transferred here from Corsica, Forcin was the deputy commander of the 2nd Foreign Paratroop Regiment, the unit that jumped into Kolwezi to clean out the Katangan rebels who occupied the town. A veteran of 23 years service, he said he was sorry he was not still with the 2nd Paratroops to be in combat.

Half the troopers in the elite force at Kolwezi were trained at Castelnaudary. Everyone in the training camp, from Forcin down to the lowest new recruit, seems to have been glued to the evening television news for the films of the operation.

Asked if he would have liked to be in on the action, a dark Yugoslav sergeant with gleaming white teeth replied, "What Legionnaire would not have wanted to go? Every night we saw our friends, guys we know, on the television. They did their job."

The Yugoslav's name does not matter. No Legionnaire's name matters much. No one in the Legion is considered to be using his own name during his first three years. After that, if he wants to, he can ask to have his original identity legally restored. Many of the men do not seek that.

Most armies allow foreigners to serve. Many have had units of foreigners. What is unique about the Legion is that it gives a man a chance for a fresh start in life. "We cover for people, that's accepted," said Forcin.

That bargain provides a major military benefit for an elite corps that serves as the French forces' equivalent of the rangers or the marines.

"Above all," said Forcin, to the rhythmic chanting of marching men outside his window, "the Legionnaire is available. The Legionnaire is ready to give his all when the whistle blows. He has broken with his past. So he is completely devoted to the new milieu he has joined. A Legionnaire does not visit his family when he goes on leave. He has cut himself off from it. A man with a family is not as available, as ready for anything you ask him to do."

Theoretically, French citizens may not join Legion ranks. But the Legion does not argue when a man says he is a French-speaking Belgian, Swiss or Canadian. There are those who say that half or more of the Legionnaires these days are actually Frenchmen.

The officers are French regular army men, but they tend to be men who start with the Legion and stay on with it as much as possible. A few Legion officers are naturalized French citizens who have risen through Legion ranks.

Germans are considered to be the second largest element, about a fifth according to well-informed guesswork. They are apparently outnumbered as group, however, by European Latins - Spaniards, Portugues and Italians.

Only in recent years have non-Europeans that is to say, non-whites, been allowed in. But the Africans, Indochinese, Pakistianis and Iranians are still only a tiny proportion.

Sitting in a cafe in Castelnaudary in the evening, the Yugoslav training sergeant was asked if a man does not fight harder for his own country. A veteran of 13 years, apparently including some combat missions that never received any publicity, he said, "The Legion is my country now. The other day, on Tito's birthday, I paid for drinks all around. I love that old man, but the Legion is my homeland. The Legionnaires are my brothers and I fight for them."

A Czech fellow sergeant sitting next to him said he had joined after coming West as a refugee from Soviet invasion of Czechoslovakia in 1968. Both men said they had heard a lot about the Legion in the communist press. "Everything they said was bad," said the Yugoslav, "but you could tell it must be a good unit, always in the thick of the fighting."

"The civilians around here make it too tough for us to do our job training the men," said one of the sergeants. "They see you pushing a man a little bit, not brutalizing him, but to get out the best he's got in him, and they go sign petitions and make complaints."

Demurring slightly, the other sergeant said, "it's wonderful what you can do with a man in the four months we have him here. He comes, he's soft, a city boy.He's 30 pounds overweight. He has no arm muscles. He puffs after running 50 yards. When he leaves he is proud of himself. His stomach is nice and smooth. He can run ten miles with a pack, and he's part of a unit."

Forcine says that about 10 out of every batch of 60 that starts training every two weeks are eliminated - usually in the first month. There are about 600 altogether training at any one time.

The Legionnaires in training do not look at all like the Beau Geste legend of the tall, handsome superman. They tend to be small, slight men. Col. Forcin confirmed that the general physical type is not now what it was when, right after World War II, German prisoners of war volunteered in droves and made up almost half of the 20-000-man Legion force fighting in French Indochina.

About a fifth of the recruits, even today, turn out to have had previous military experience.

"The Superman," said the Czech sergeant, "is not necessarily the best soldier. He thinks he's better than the others. He is an individualist, undisciplined. Maybe in hand-to-hand combat, a guy like that could overpower you. But our guys are a lot better in unit operations. We take small, ordinary men and get the best out of them."

The Legion today is down to eight regiments - about 8,000 men. Originally formed in Algeria in 1831. The Legion was designed to keep order in France's North African empire. Without an empire, France still has half of the Legion overseas.

Aside from headquarters, transferred from Sidi-Bel-Abbes in Algeria to the Marseilles area, two regiments still in Corsica and a tank regiments in southern France, the main units are in Djibouti, Guyana and at the French atomic test center in the South Pacific.

The Legion's prestige unit, even before the Zaire operation, was the 2nd Paratroops stationed in Corsica. Thirty of the training sergeants and officers at Castelnaudary were on loan from the 2nd Paratroops, and they rejoined it for the Kolwezi operation.

The Legion goes in for intensive language training of non-French-speaking recruits. Unlike other members of the French forces. Legionnaires must repeat any question from a superior before answering. This is designed as a guarantee that the question was understood.

Officially, Legionnaires are single.