Which Narnia book introduces the Pevensie children entering the world through a wardrobe?

The Lion, the Witch and the Wardrobe introduces the Pevensie children entering Narnia through a wardrobe.

C.S. Lewis’s novel was first published in 1950 and follows Peter, Susan, Edmund, and Lucy Pevensie. During the Second World War, the children are sent away from London to stay with Professor Kirke in the countryside. Lucy discovers that a wardrobe leads to the snowy land of Narnia.

In Narnia, the children encounter the faun Mr. Tumnus, the White Witch, and the great lion Aslan. Edmund’s betrayal and later rescue form a major part of the story, while the four children eventually become rulers of Narnia. The book established many of the series’ most recognizable characters and themes.

The Magician’s Nephew explains Narnia’s creation but was published later. Prince Caspian and The Voyage of the Dawn Treader continue the Pevensies’ adventures. Lewis’s original publication order therefore begins with the wardrobe story, even though some later reading orders place another book first.