France's valiant underground; Soldiers of the Night: The Story of the French Resistance, by David Schoenbrun. New York: E. P. Dutton. $15.95.

In June 1940 an emotionally unready and politically divided France collapsed in the face of Germany's highly mobile armored warfare. After an armistice of defeat, the French expected that Britain would be next to fall, so the doddering Marshall Petain was able to lead France into partnership with the Nazis.

Only when the tide of battle had swung in favor of the Allies did significant numbers of the French begin to have doubts about the wisdom of collaboration with Hitler's "New Order." It's considered bad from to say it, but only a noble few -- a mere 5 percent of the population -- actively resisted their German occupiers before the D-Day landings in June 1944.

With his "Soldiers of the Night," former CBS Paris bureau chief David Schoenbrun gives us an excellent, solidly researched account of the struggle waged by that gallant handful who sabotaged railroads and power plants, rescued Allied fliers and Jewish fugitives, assassinated German and Vichy officials, then fought pitched battles elite Wehrmacht formations.

Schoenbrun is no stranger to the Resistance. In 1943, as an officer in the US Army's psychological warfare section, he made radio broadcasts from Free French headquarters in Algiers to the people of occupied France. The next year, as a combat radio correspondent, he accompanied Allied troops landing on the Riviera, then covered the liberation of many towns in southeastern France.

With great objectivity and verve, Schoenbrun chronicles the often muddled, uncoordinated efforts of the Resistance through the four dark years of Nazi occupation. Systematically and factually, he explains the workings on the fragmented organizations that kept on fighting in spite of the Germans' rutless attempts to stamp them out.

We sense the anguish of those who made the first courageous steps in setting up a network of Resistance cells. It is certain that patriots like Henri Frenay , founder of the movement called "Combat," had to surmount personal doubts, first of all. They were seen as terrorists by so-called "good Frenchmen." Schoenbrun writes that Frenay's mother threatened to denounce her own son -- a demobilized Army officer -- to the police: "I love you dearly, but I believe that patriotic duty comes before maternal love."

In July 1940, Charles de Gaulle, then a young general condemned in absentia for desertion and treason, was struggling to gain recognition as the leader of the Resistance abroad. Meanwhile, in France, the Resistance of the interior was springing up.

Schoenbrun gives a detailed account of how the earliest Resistance group was formed at the Musee de l'Homme by Boris Vilde, a young linquist on the staff of that Paris museum. The group consisted mainly of liberal intellectuals -- most of them Vilde's fellow employees. They published clandestine tracts debunking the Petain regime, and set up an underground railway so that downed Allied pilots could be guided across the demarcation into unoccupied southern France.The group also obtained carefully drawn sketches of German submarine pens at Saint-Nazaire, then managed to pass the information on to London.

But the fate of this early underground cell exemplifies the danger that hung over the heads of all who opposed the German occupation. Given away by paid informers, the Musee de l'Homme resistants were arrested by the Gestapo, then tried and convicted.

Oddly enough, the author relates, it was Vichy itself that spurred enlistments in the Resistance. In the spring of 1943 pro-Nazi Premier Pierre Laval agreed to supply German war industry with 250,000 more French workers. Result: thousands of youths who refused to answer labor conscription notices took to armed camps in the mountains of France.

In general, the Maquis, as they were called, had few weapons, for none of the Allies -- including the Free French -- were willing to send substantial quantities of arms to underground groups that they didn't really control.

The Resistance tried to attract former French Army officers into the guerrilla movement, but this effort met with little success. One notable exception, though, was the Maquis of the Platteau des Glieres, near the Swiss border. There, late in 1943, a ragged regiment sprang into being around a nucleus of career officers and NCOs.

In defiance of Henri Frenay's orders to keep guerrilla units small and mobile , a former Chasseur Alpin lieutenant, Theodose Morel, assembled 457 teen-aged fugitives from the forced labor program, exiled veterans of the Spanish Republican Army, and Jewish refugees. Surrounded by 10,000 German and Vichy troops, the resistants atop the mile-high plateau fought as long as they could pull a trigger or fix a bayonet. But after two months at below-freezing temperatures, pounded incessantly by Heinkel bombers and heavy artillery, the Maquis leader reluctantly ordered his men to break out under cover of darkness. One hundred and sixty maquisards were taken prisoner -- many to be executed summarily. The massacre of Glieres, writes Schoenbrun, was "a defeat of arms, but a victory of souls." It typified the enormous courage in the fact of grave risk that would be played out again and again by the men of the Resistance.