Which C.S. Lewis novel was the first Narnia book in the series’ internal chronology?

The Magician’s Nephew is the first Narnia book in the series’ internal chronology.

Published in 1955, it tells how Digory Kirke and Polly Plummer travel between worlds and witness the creation of Narnia. The story introduces the magical rings, the Wood between the Worlds, the character Jadis, and the song by which Aslan brings Narnia into being.

The novel was published sixth, after The Lion, the Witch and the Wardrobe and four other books. Its events nevertheless occur before the adventures of the Pevensie children. Many modern editions therefore label it Book One, while publication-order lists keep it as Book Six.

This distinction explains why readers may encounter two different numbering systems. The answer remains The Magician’s Nephew when the question asks about the fictional timeline, not the order in which Lewis released the novels.