Which C.S. Lewis novel was first published in 1950 and introduces Narnia through a wardrobe?

The C.S. Lewis novel first published in 1950 that introduces Narnia through a wardrobe is The Lion, the Witch and the Wardrobe.

The book follows Peter, Susan, Edmund, and Lucy Pevensie, who discover a passage into Narnia inside a wardrobe. Lucy is the first of the four to enter the snowy land, where the White Witch has imposed a long winter. The story introduces Aslan, the great lion who becomes its central heroic figure.

The novel was published in the United Kingdom by Geoffrey Bles on 16 October 1950. It was the first Narnia book published, although Lewis later wrote The Magician’s Nephew as a prequel about Narnia’s origins.

The wardrobe itself was inspired partly by Lewis’s interest in imaginative transformation and old-fashioned furniture. Its role is specific to this story, so it should not be confused with the rings, pools, or other portals appearing elsewhere in the series.