VERA BRITTAIN was born in 1894 into a world where the carpets were thick, clothes elaborate, housemaids numerous, and books few. Looking back on it, she compared herself to a sensitive plant, "securely sheltered in the greenhouse warmth of bourgeois comfort and provincial elegance." Her greatest wish as she grew up was to break out of the greenhouse and become someone of consequence: an educated, thinking woman, prepared, as she pompously wrote in her diary at 19, "to extend love, to promote thought, to lighten suffering, to combat indifference, to inspire activity." All this she achieved, as well as her wish to be a writer -- modestly popular if not quite first-rate. She wrote one brave book, however, first published in 1933, that has come back, thanks to Masterpiece Theater, to confront another age.

Testament of Youth is an unflinching account of the early life of an Englishwoman whom circumstances and conscience made an eloquent witness to a war that in this century of horrors remains the most savage, futile, and incomprehensible of any. Vera Brittain lost everyone she loved, including her fiance and her only brother, and as a Red Cross nurse supped full on horror in a front-line hospital, pushing intestines back into gaping bodies, cleaning gangrenous wounds, bandaging quivering bloody stumps, holding the hands of dying men, English and German. "It is quite impossible to understand," she wrote in the midst of it, "how we can be such strong individualists, so insistent on the rights and claims of every human soul, and yet at the same time countenance (and if we are English, even take quite calmly) this wholesale murder, which if were applied to animals or birds or indeed anything except men would fill us with a sickness and repulsion greater than we could endure."

When the Great War began she perceived it only as a vexation. She was 20, "mentally voracious," and yet was expected to contend herself with piano lessons while her musically gifted younger brother Edward was destined for Oxford. But in October 1914 it was Vera who went to Oxford, having passed examinations brilliantly and won a scholarship -- "God have pity on my fierce excitement!" she wrote in her diary -- while Edward went instead to officers' training camp. In her college Vera sat up at night discussing religion and genius; she joined societies promoting women's suffrage, peace and Bach; she was the "lion" of her class. And she was in love.

The beloved was Roland Leighton, her brother's clever schoolmate, who had also passed up Oxford for an army commission. The lovers could rarely be together, and when they were, were chaperoned, but their letters were full of poetry, thoughts on immortality, and rapt self-examination. After such abstract intimacy, it was hard to know what to say when they met face to face. "Why don't you say something?" a chaperone asked. "Is it too deep for words?" It was.

Roland, courting "Heroism in the Abstract," got himself sent to the front, confident he would come back, perhaps with a dignified empty sleeve; he didn't imagine paraplegia or blindness. From inside his trench he wrote, "The sun is a shield of burnished gold in a sea of turquoise; the bees are in the clover that overhangs the trench. It is a pity to kill people on a day like this." At Oxford Vera racked her brains to arrive at a philosophy that could give meaning to the catastrophe that had overturned her world. To stop thought in hard physical work she left college to be a Red Cross nurse. The girl who didn't know how to boil an egg and had never seen a man or boy undressed found herself ministering to the basic needs of wounded men. "Short of actually going to bed with them, there was hardly an intimate service I did not perform."

Roland had one more leave before his inglorious end, but during their days together they remained sullen and irritable, speechless with dread and desire. After a forlorn, desperate kiss in the railway station they were carried apart. Just before a Christmas leave in 1915 he was killed. It was not the hero's death in battle he had fancied, but a spurt of machine gun bullets, while he was mending barbed wire, that tore his guts to pieces and severed his spinal cord. He had no final word for Vera; he had never told her he had turned Catholic a few months earlier. He wasn't yet 20; they had hardly known each other; their love was a romance. Yet she never relinquished it, and remained defiantly proud of having loved him with a passion she never knew again or wanted to know.

After he died she struggled on in the surgical ward, among a surreal hubbub of groans and cries half-masked by the blare of phonograph records, Harry Lauder songs or "When Irish Eyes Are Smiling" -- music to die by. One day, among a shipment of casualties from the Somme, she found her brother Edward. The unassuming musician who felt no vocation for heroism had led an attack, in spite of wounds, with a courage that won him the Military Cross -- an honor Roland had thought more desirable than the Noble Prize.

Vera's early doubts about the war hardened. Why were men dying in their millions? The only reason most soldiers could come up with was, "We're here because we're here because we're here," snub to the tune of "Auld Lang Syne." "Between 1914 and 1918," Vera later reflected, "young men and women, disastrously pure in heart and unsuspicious of elderly self-interest and cynical exploitation, were continually rededicating themselves . . . to an end that they believed, and went on trying to believe, lofty and ideal . . . Undoubtedly this state of mind was . . . 'hysterical exaltation' . . . but it had concrete results in stupendous patience, in superhuman endurance, in the constant reaffirmation of incredible courage. To refuse to acknowledge this is to underrate the power of those white angels which fight so naively on the side of destruction." "Never such innocence again," says Philip Larkin's poem about that war.

After a tour of duty in Malta, nursing U-boat victims the blue Mediterranean incessantly gave up, she returned to London, gliding en route through France on a luxurious express train. As if the lunar landscape of the trenches, stinking with the rotting corpses of horses and men, did not exist a few miles distant, in Paris she could see the sights, shop for a cigarette case, and eat pate de foie gras sandwiches. But in the England countryside she heard a periodic thumping like a tremendous heart-beat" -- the guns across the Channel.

She was finally confronted with the enemy in a French war hospital. For the entrenched British soldier, Germans were shadowy figures sometimes seen fitting in the dawn or dusk; for Vera they were shattered, dying boys gazing at her with pleading eyes. One held out an emaciated hand to her. She took it, "thinking how ridiculous it was that I should be holding this man's hand in friendship when perhaps, only a week or two earlier, Edward up at Ypres had been doing his best to kill him." Yet it was possible to take an evening's walk away from these scenes of anguish to eat an omelette in a garden scented with sweetbriar.

In the summer of 1918 Vera was called home to keep house for her mother. "The strain all along" -- too few servants, too little meat and butter -- was too much. Vera thought bitterly of what "strain" had meant to her: "gassed men on stretchers, clawing the air -- dying men, reeking with mud and foul green-stained bandages, shrieking and writhing in a grotesque travesty of manhood." It was at home she heard of her brother's death, shot through the head.

Everyone she loved was dead, all her ideals "trampled into the mud which covered the bodies of those with whom I had shared them." The endless war stopped at last -- "a striving, and a striving, and ending in nothing." Numbly she went back to Oxford, switching from English to history, hoping to "understand how the whole calamity had happened, to know why it had been possible for me and my contemporaries . . . to be used, hypnotized and slaughtered." She was greeted coldly at her old college and shunned by a younger generation of students to whom the war was old hat. She began to be haunted by the belief that she was growing a witch's beard. The "psychological shutter" that has closed off the war's daily agonies no longer worked.

After getting her degree, she wrote novels politely considered promising and lectured with great success. When the exquisitely pretty and fashionable lecturer showed up (her careful descriptions of her clothes must be fascinating to anyone interested in costume), she was apt to be told, "You don't mean to say you're Miss Brittain?" Four times a week for three years she spoke up for the League of Nations, the peace movement, and women's liberation.

She had accepted spinsterhood, but a persistant admirer, whom she archly calls "G.," gradually persuaded her to be his wife. She was reluctant. "Should I, who had once dedicated myself to the dead, assume yet further responsibilities towards the living?" In 1925 she finally married the distinguished political philosopher, Sir George Catlin, and lived another 45 years, writing, lecturing, and sitting down for peace in Trafalgar Square.

Through a product of the '30s, Vera Brittain's "testament" is written in the rather fussy, peri-phrastic language of the world before the Great War that divided history, she believed, as decisively as B.C. and A.D., but it is no less affectingly honest and heartrending. It's now impossible to imagine the innocence with which her generation answered what they solemnly described as the call of God, King, and Country; but not impossible to envy them their generous, fatal idealism.