What was the first thing that Geoffrey Chaucer wrote?

Geoffrey Chaucer's earliest known work is "The Book of the Duchess," composed in the late 14th century. This poem is an elegy written in honor of Blanche of Lancaster, the wife of John of Gaunt, and reflects themes of love and loss. It showcases Chaucer's developing poetic style and his ability to blend narrative with emotional depth. While there may be earlier works attributed to him, "The Book of the Duchess" is generally recognized as his first significant literary contribution.