Which C.S. Lewis book introduces the character Prince Caspian?

C.S. Lewis’s book Prince Caspian introduces the character Prince Caspian. It is the fourth book in the original publication order of The Chronicles of Narnia, appearing in 1951 after The Lion, the Witch and the Wardrobe.

The story follows Peter, Susan, Edmund, and Lucy Pevensie when they return to Narnia and discover that centuries have passed there while only a year has passed in their world. Narnia has been ruled by the Telmarines, and Caspian is resisting his uncle Miraz, who has seized the throne.

The book is sometimes numbered second in reading orders based on the fictional chronology of Narnia. That difference explains why readers may see it called either the second or fourth Narnia book. Its full title is Prince Caspian: The Return to Narnia, and its central conflict concerns rightful rule, memory, and the restoration of the old Narnian order.