Solzhenitsyn fought in the Red Army during World War II. He became a captain before he was arrested in 1945 for criticizing Joseph Stalin in letters to his brother in law. He was imprisoned for eight years, from 1945 to 1952, using the draconian Article 58 law. He spent time in a Sharashka or a white-collar prison slave-labor compound. He wrote about this in The First Circle.
The novel about Ivan Denisovich brought the Soviet system of forced labor to the attention of the West, but it was his monumental history of the massive Soviet concentration camps for both criminal and political prisoners that made it impossible for either the West or the Soviet Union to ignore the realities of the Communist regime. No longer was this an issue for anti-communists only; all Western democracies had to confront it.
In 1974, Solzhenitsyn was exiled, after the KGB had found the manuscript for the first part of "The Gulag Archipelago". He first settled in Zürich, Switzerland, and later in Vermont, USA. In 1990 his Soviet citizenship was restored, and in 1994 he returned to Russia.
Despite an enthusiastic welcome followed by respect for his privacy, he had never been comfortable outside his homeland. However radical he might have been in the USSR, outside that context he appeared to some to be a reactionary, particularly in his Russian nationalism and his religious orthodoxy. At any rate, he was hardly the "Cold War prize" some had thought him.
His ex-wife Nastasya Resehtovskaya, wrote a book about her life and their relationship. In this book she bitterly talks of some of his less charming characteristics. She says he wanted to have sexual affairs with other women because he felt it would give him the inspiration to write another book.