Krig og fred udspiller sig i 1805-1820 omkring Napoleonskrigene. På et fintvævet baggrundstæppe af historiske begivenheder fortæller den om fem familier i Rusland og forbindelserne mellem dem. Alliancer og konflikter, giftermål og utroskab breder sig gennem de russiske saloner og sætter familierne på en række voldsomme prøvelser. Rundt om denne fortælling oprulles et vældigt panorama over Rusland og Europa, mens krigen rykker tættere og tættere på. Tolstoj bevæger sig ubesværet fra nationens liv til den mindste sjælerørelse, fra generalernes slagplaner til soldatens blodige virkelighed, fra funklende baller og indviklede intriger til bondelandets grove og enkle liv. Fra krig til fred og tilbage igen og igen og igen.
I Krig og fred sammenfletter Tolstoj historiske scener og personer fra Napoleonskrigene og felttoget i Rusland med fiktive karakterer og påviser ultimativt den forskel, et enkelt menneske kan udgøre for en hel nation.
Lev Nikolayevich Tolstoy (Russian: Лев Николаевич Толстой; most appropriately used Liev Tolstoy; commonly Leo Tolstoy in Anglophone countries) was a Russian writer who primarily wrote novels and short stories. Later in life, he also wrote plays and essays. His two most famous works, the novels War and Peace and Anna Karenina, are acknowledged as two of the greatest novels of all time and a pinnacle of realist fiction. Many consider Tolstoy to have been one of the world's greatest novelists. Tolstoy is equally known for his complicated and paradoxical persona and for his extreme moralistic and ascetic views, which he adopted after a moral crisis and spiritual awakening in the 1870s, after which he also became noted as a moral thinker and social reformer.
His literal interpretation of the ethical teachings of Jesus, centering on the Sermon on the Mount, caused him in later life to become a fervent Christian anarchist and anarcho-pacifist. His ideas on nonviolent resistance, expressed in such works as The Kingdom of God Is Within You, were to have a profound impact on such pivotal twentieth-century figures as Mohandas Gandhi and Martin Luther King, Jr.