What is the name of the first book published in C.S. Lewis's 'The Chronicles of Narnia'?

The first book published in C.S. Lewis's The Chronicles of Narnia is The Lion, the Witch and the Wardrobe.

Geoffrey Bles published the novel in the United Kingdom on 16 October 1950. It introduces Peter, Susan, Edmund and Lucy Pevensie, who discover that a wardrobe leads from wartime England into Narnia, a land trapped in winter by the White Witch. The children eventually join Aslan and help restore Narnia's rightful order.

A common source of confusion is The Magician's Nephew. Although it was published in 1955, it is set earlier in Narnia's internal chronology and is numbered first in many modern editions. The Lion, the Witch and the Wardrobe remains the first published volume and was also the first Narnia book Lewis completed and released.

The book was illustrated by Pauline Baynes and was followed by Prince Caspian in 1951. Its publication order gives readers the original introduction to Narnia, Aslan and the Pevensie children before later books expand the world's history.