Olivia Manning is the female novelist we have unjustly forgotten, argues Deirdre David in this clear-eyed, unsentimental and riveting biography of the author of Fortunes Of War.

One of a group of women novelists who came to fame in the 1960s, Manning has suffered by comparison with her contemporaries, Iris Murdoch, Muriel Spark, Doris Lessing and Elizabeth Bowen. It is difficult to find an "appropriate literary slot" for this woman who worked as a typist and wrote short stories and novels in her spare evenings. She has no literary lineage. She did not belong to any "school".

However, David is right to say that all of this makes her a more fascinating subject for a biography. God loves a trier, so they say, and no-one tried harder than Manning. Born in Portsmouth to a frustrated and bullying mother and a genteel but rather impoverished naval officer father, she came from a non-literary background, and at 16 had to leave school to help with the family finances. Yet all through her twenties she educated herself by reading the best books (she was particularly keen on Virginia Woolf), making notes and trying her hand at fiction. As David emphasises, "no-one advised her, few encouraged her, yet after typing all day in a solicitor's office, she managed to write an enormously long novel ... and valiantly sent the script off to Jonathan Cape ..."

Hamish Miles, an assistant editor, rejected that novel but asked to meet her so, anxious to escape her mother and discover the wider world, Manning soon abandoned Portsmouth for London, where she took menial jobs to pay for her keep.

Miles was the crucial link: at last she had some encouragement from someone with the right connections. They developed a "mentor-acolyte relationship" which inevitably, perhaps, became sexual, and she gave up the jobs to review freelance, helped by Miles's influence. When Cape finally accepted her manuscript, The Wind Changes, David notes, "she was able to eat moderately well, cut back on the freelance work, and imagine that she might, one day, become a full-time successful working writer."

Was hers a conventional or unconventional route to publishing success, a brave or a foolhardy act? Whichever, she turned it to her advantage and began to meet other writers, making a particular friend in Stevie Smith and her future husband, Reggie Smith, then a British Council worker, soon to be a BBC producer. After a speedy courtship and marriage, he was back teaching in Bucharest, Manning with him. That was in 1939. As Europe crumbled in the face of war, Manning and Smith fled, first to Athens, then Cairo, all their extraordinary experiences giving Manning the material she would need later for her celebrated war novels.

However, she had a few things to learn about her philandering husband first, and the disappointment of a late miscarriage that prevented her having any more children tested their marriage, but they stood by each other. Manning continued to write, but depressive periods would hamper her creativity (although not in as extreme a form as her heroine, Woolf).

During the 1940s she would produce generally well-received novels, but her own reviews were eye-catching and could even be venomous. By the 1950s, she was already beginning to fear she was being edged out by the Murdochs, Lessings and Sparks (Elizabeths Bowen and Smart felt the full force of her wrath, too). She favoured a realist, pared-back style, free of metaphor that ironically would come into fashion with the Angry Young Men of the 1950s. No-one, it seemed, found an "angry young woman" quite as appealing, yet Manning relished the more "impersonal" and "masculine" aspects of her writing.

David pays tribute to Manning's position as a "self-supporting woman writer at a historical moment when the more conservative elements in society aimed at restoring women to domesticity".

It wasn't easy. In a cry that anticipates problems writers face today, she asked one woman at her publishers, "if her sales have been 'so terrible that Heinemann's have lost all faith in me? I feel I have been a disappointment ... I really don't know what to do to make myself sell'."

This was all before the success of her war novels, The Balkans Trilogy (also known as Fortunes Of War) and The Levant Trilogy, but even after that she would complain that she never got the accolades her female contemporaries received. She could be a demanding friend, too – "never enough attention, never enough love", she would complain of those closest to her, and she rarely forgave a slight (Stevie Smith got it in the neck after she died and Manning wrote about their long friendship).

She was a classic outsider, not born to literary greatness but having to work for it, never on the inside where the Oxbridge set were, or at the most fashionable literary parties. In that sense, though, she speaks probably to most of us.