Which 1950 novel began C.S. Lewis's Chronicles of Narnia publication sequence?

The Lion, the Witch and the Wardrobe began C.S. Lewis's Chronicles of Narnia publication sequence in 1950.

The novel introduces the world of Narnia through four English children who enter it through a wardrobe. Peter, Susan, Edmund, and Lucy encounter the White Witch, the faun Mr. Tumnus, and the lion Aslan. Its mixture of adventure, mythology, and Christian symbolism made it Lewis’s most widely recognized children’s novel.

Lewis published the books in the order he wrote them, beginning with The Lion, the Witch and the Wardrobe. Later editions often print the series in an internal chronological order that starts with The Magician’s Nephew, which is set earlier in Narnian history. That ordering can cause confusion when a question asks which book was published first.

The first edition appeared in 1950, with illustrations by Pauline Baynes. Six additional Narnia novels followed, completing the seven-book series.