All’s fair in love and war

The origin is attributed to the poet John Lyly in his novel Euphues: The Anatomy of Wit published in 1579. Lyly wrote, “Any impiety may be committed in love, which is lawless.” In the sense that anything goes in achieving success in pursuit of love. In Shelton’s translation of Don Quixote in 1620, the concept of war was added, but the exact phrasing, as we know it today, only appears during the mid-19th century.