The Horn of Queen Susan Pevensie of the Kingdom of Narnia was a magical hollowed ivory animal horn used in times of emergency to call for help. It was given to Susan by Father Christmas just before the Winter Revolution, who said if it was blown, help would always come. Susan first used it when she was attacked by Maugrim the wolf as the Battle of Aslan's Camp was about to break out. Peter heard it and saved her life. The sound of it was described as "like a bugle, but richer".
Queen Susan left her horn at Cair Paravel when she went to the Lantern Waste to hunt the White Stag, and after the Pevensies' disappearance, the horn became lost for many years. Eventually it was rediscovered by half-dwarf Doctor Cornelius around the Narnian year 2300. Shortly before the Narnian Revolution, Cornelius passed the horn on to Caspian X. The legend of its magical ability to summon aid was known to Cornelius, and after much debate, Caspian blew it in order to free the Narnians from the Telmarine conquest.
The horn magically transported the Pevensies back to Narnia. They reappeared at Cair Paravel and traveled to meet Caspian and his army at Aslan's How, eventually succeeding in recalling Aslan and restoring the Narnian throne to Caspian. Later, when Caspian set out on his voyage on the Dawn Treader, he gave the horn to his regent Trumpkin to use if any great need fell on the land in the king's absence. The horn passed many hands and stories over the years. Its final fate after the destruction of Narnia is unknown, as its original owner, Susan, did not return to Narnia in time to reclaim it and bring it to Aslan's Country.