THE SPANISH Civil War of 1936 to 1939 was not only a civil war, it was also a full-scale dress rehearsal for the European war of 1939 to 1945. It was a testing ground for new weapons -- the Stuka divebomber and the Luftwaffe 88mm. cannon, for example -- and new tactics -- German and Russian tank generals won their spurs in Spain. It was also an eerily exact preview of the lineup of national forces that were later to face each other on the battlefields of North Africa and Europe. The Nationalists had the massive backing of Fascist Italy and Germany, while on the Republican side, in addition to Russian tank specialists and pilots, there were volunteer formations of Frenchmen, Englishmen, Poles, Yugoslavs and Americans who, together with anti-Fascist German and Italian exiles, constituted the bulk of the five International Brigades of the Republican army.

The American unit, the Abraham Lincoln Battalion (sometimes referred to as the Lincoln Brigade), first went into action in Febrary 1937, under the command of a young man called Robert Merriman, a graduate student and instructor in economics at U.C. Berkeley. In 1935, together with his wife Marion, whom he had met and married at the University of Nevada, he went to Moscow on a traveling scholarship to study the Soviet system.

Like many young people in those years of the Depression, he was impressed by the Soviet claim that the U.S.S.R. had abolished unemployment; in the U.S. one third of the nation was unemployed and many of those who were employed worked in conditions hard to imagine today. In an autombile factory, for example, where Merriman worked for a while to supplement his Berkeley salary, workers were not allowed to leave the assembly line to urinate -- they had to relieve themselves on the spot or wait until the end of the shift.

Residence in Moscow and travel in eastern Europe did not convert him to communism but did make him acutely aware of the growing strength and influence of the Fascist powers; Spain seemed to him, as to so many others, a place where Fascism might be given a decisive setback. Leaving his wife in Moscow, he went to Spain to offer his services; since he had completed the ROTC course at the University of Nevada and held a reserve commission in the U.S. Army, he was appointed second in command of the newly formed Lincoln Battalion, which was attached to the XVth International Brigade.

Just before the battalion went into action, its commander had to be removed as incompetent; Merriman was in command when the Americans played their part in the costly Jarama battles that blocked Franco's attempt to cut Madrid's lifeline to Valencia. They suffered heavy losses in what Ernest Hemingway later called an "idiotic, stupidly conceived and insanely executed attack in the hills above the Jarama River"; Merriman vigorously protested the orders from brigade headquarters but was overruled and went forward at the head of his men. When the battalion was withdrawn, there were 137 dead and almost 200 wounded, among them Merriman himself.

Later that year, recovered from his wound and promoted to chief of staff of the brigade, he was with the battalion in the bitter fighting at Belchite in Aragon, where he was wounded again, lightly this time, leading an assault and later in the winter fighting at Teruel. In March 1938 the Nationalists, reinforced by Italian regulars and equipped with new German artillery and planes, broke through the Republican front to reach the Mediterranean and cut the territory of the Republic into two separate zones. The Lincoln Battalion fought stubbornly but it was overrun and surrounded; when the survivors who had made their way out to safety were reunited, Merriman was not among them. He was never heard from again.

This book, written by his widow in collaboration with a Pulitzer Prize-winning journalist, is an account of Merriman's short life, based on her own memories and diaries, on the battle diaries of her husband which, with some presentiment of his death, he had handed over to her the last time she saw him alive, as well as on news dispatches (those of Ernest Hemingway to The New York Times for example) and eye-witness accounts by surviving members of the Lincoln Battalion. It is a striking portrait of an intellectual who displayed in dangerous action not only exemplary courage but a talent for command -- the salient characteristics of Hemingway's Robert Jordan, the hero of For Whom the Bell Tolls. BUT THE BOOK tells also another story: that of Marion herself. She did not stay behind in Moscow for long; when she received a cable, two months after her husband's departure -- "Wounded; come at once" -- she made her way to Spain in spite of the cold refusal of one-time friends at the U.S. Embassy in Paris to help her, and joined her husband at the hospital in Murcia. Once there she insisted on staying and was enrolled as a volunteer in the XVth Brigade with administrative duties.

She saw Madrid under bombardment and the corpses stacked in the ruined houses of Belchite; she gives vivid accounts of Hemingway and Dos Passos in Madrid and of life in the brigade hospitals and training centers. Later, sent back to the United States to help raise money for ambulances (the only form of aid to the Republic permitted under U.S. regulations) she heard the news that her husband was missing in action. In a pattern of protracted agony that was to be re-enacted later by wives of Americans reported missing in World War II, Korea and Vietnam, she lived for months between fears and hopes until finally there was no room left for either. Eventually she married again, raised a family of three sons and worked in the administration at Stanford University. When her second husband died she found herself at last able to write this moving book, which John Kenneth Galbraith, Merriman's fellow student at Berkeley, rightly calls "the story of the life and death of the first hero of World War II."

Bernard Knox fought in the French Battalion of the XIth International Brigade at Madrid in the winter of 1936.