Destrier

"Destrier has always served me well. You are in good hands." "Or hooves."

- Caspian and Susan

Destrier was the black horse that belonged to Caspian X. He was born and bred in Narnia, but was just an ordinary dumb horse, and not a talking one.

Caspian's teacher, Cornelius, brought Destrier to him so that he could use it to escape his uncle's kingdom, which he did shortly before the Narnian Revolution began.

Unfortunately, after he fled the kingdom, Caspian was knocked off Destrier during a storm, and was taken in by the Old Narnians, while the frightened horse ran back to Miraz's Castle, alerting the Telmarines of Caspian's escape.

Film Adaption
According to the 2008 movie, the same thing happened just as it did in the book, except that Caspian was able to later reclaim Destrier from the castle after the failed raid attack. He used him to escape, along with everyone else, when Peter signaled the retreat.

Shortly after, he lent Destrier to Susan and Lucy, when they headed out to go locate Aslan.

After Lucy successfully found Aslan, and jumped off the horse to go speak with him, the disposition of the horse afterwards is not mentioned. Caspian was seen, though, riding a black horse that was similar to Destrier, into the Castle of Caspian after the Second Battle of Beruna.

Trivia

 * The word "Destrier" means "War-Horse".