Vie des douze Césars
It is unknown why Tolstoy changed the name to "War and Peace". He may have borrowed the title from the 1861 work of Pierre-Joseph Proudhon: ("War and Peace" in French). The title may also be another reference to Titus, described as being a master of "war and peace" in "The Twelve Caesars", written by Suetonius in 119.