JEAN LACOUTURE has composed a dazzling, complex work that appears in the guise of a biography of L,eon Blum. But this book is far more. It is a biography of a social movement and its time, of the bid for power by the French working class between the two world wars and its failure. As the guiding force for France's socialist movement for much of this century and prime minister in the Popular Front governments of the mid-1930s, Blum unites and illustrates the ideas and the misunderstood era that are Lacouture's true subjects.

France between the wars was a nation riven by social and political conflicts that ultimately exhausted the national will. Although many Americans seem to believe that France surrendered to the Germans out of weakness and fear in June 1940, France did not simply collapse. It had been undermined by years of living under the threat of its own civil war. Lacouture's richly detailed account is essential for understanding the roots not only of the disaster of Vichy but also why the nation would ultimately turn to de Gaulle for salvation not once but twice.

Leon Blum either found or inserted himself at the center of the conflicts that would divide Frenchmen into warring economic and political clans. An intellectual passionate about literature and esthetics rather than power, a leftist who refused to justify the suppression of liberties and rule by force in the name of a better future, a Jew who moved with ease through much of French society but who did not assimilate, Blum clung to the middle ground and to moderation with a tenacity that made him the target, and enemy, of both left and right.

It was the Dreyfus Affair that drew Blum, who had begun to make a reputation in Paris as a brilliant essayist, into politics and convinced him and his political mentor, Jean JaurMes, that socialism could be made into a broad culture infused with morality that would transform the vengeful and greedy politics of turn-of-the-century France.

The persecution of Captain Dreyfus by the French army command assaulted Blum not only as a Jew but also as a lawyer. It fueled his determination to seek a political antidote to injustice, and after JaurMes' assassination, in 1914, Blum sought to mold a Socialist Party that was vaguely Marxian but not Marxist as the instrument that could accomplish this task.

The times did not reciprocate with promising conditions for such moderation. Blum was attacked with equal venom by France's fascists and by the communists, who purged Blum and his followers from the international Marxist movement in 1920 because of their moderation. He saw the moral victory the French socialist cause gained from the Dreyfus Affair eclipsed by the crude anti- Semitism of the Vichyites, who in 1940 helped the Nazis send Blum to Buchenwald. (He survived the camp and died in 1950 at the age of 78). His warnings that French vindictiveness in the Ruhr would create the conditions for the rise of a Hitler infuriated and was ignored by French conservatives, just as his warnings that France would have to fight after Hitler had come to power alienated the pacifists and internationalists in his party.

Lacouture acknowledges that Blum's career--particularly the Popular Front's failure to fight in Spain against fascism during the Civil War--raises the question of whether well-meaning intellectuals can govern in difficult and dangerous times. "Is the intellectual condemned to the role of Hamlet? Giving great importance to analysis, is he condemned to devote too much time to it?" His answer is a summary of Blum's importance to France in this century:

"Blum, more than any other man of his time, attempted to reconcile the conquest of justice and the defense of freedom. The fact that the balance between the two is constantly unstable, that whatever is lost by one is not necessarily gained by the other, that nothing which is conquered on one front allows one to turn away from the other--all of this Blum knew well. . . . He believed that, provided one does not despise, lie, ridicule, one can persuade. . . . He did not believe in the political virtue of evil."

While Lacouture, one of France's most accomplished writers of political biography, has succeeded in giving us a good bit more than his subject, Bernard Ledwidge has inevitably had to give us a good bit less than the historic giant of a figure he has chosen to profile. The greatness of Charles de Gaulle eludes us in the pleasant and mildly informative biography Ledwidge has written.

A diplomat who observed de Gaulle from the British embassy in Paris in the 1960s, Ledwidge adds little new contextual analysis of de Gaulle's leadership and vision, while going back over ground available elsewhere.

The best section of the book covers de Gaulle's use of weakness as strength during his exile in London and North Africa in World War II. Quickly realizing that he was far too weak to make concessions to his British hosts and their American friends on any points involving the Free French forces de Gaulle claimed to command, de Gaulle developed the obstinate, determined fashion of dealing with London and Washington that most Americans still associate him with. To survive, he had to confront, challenge and manipulate Churchill constantly. That he was able to do so is a testimony to the wisdom and skill of both men.

Ledwidge overdraws the justified bitterness that de Gaulle felt over his treatment by Roosevelt, but not by much. He has a good grasp of the general's relations with those whom he derided as "les Anglo-Americains," and could haveecarved out a smaller, more innovative volume on that topic except that an excellent study already exists (John Newhouse's De Gaulle and the Anglo-Saxons). For the specialist, Ledwidge does add interesting interpretations of de Gaulle's controversial Quebec performance in 1967 and his flight to West Germany during the May 1968 upheaval that ultimately felled the largest oak in the French forest.