Horn of Gondor

From Wikipedia:

Horn of Gondor

An heirloom of the Stewards of Gondor, also called the Great Horn.

The horn was made by Vorondil the Hunter in the Third Age. Vorondil hunted oxen all the way to the Sea of Rhûn and fashioned the horn out of one of the oxen's horns. (Tolkien calls the beast one of the "Kine of Araw".) It was passed down through the line of the Stewards of Gondor.

During the War of the Ring, Boromir, elder son of Denethor, possessed the Horn of Gondor, just as it had been borne by the eldest son of the Lord Steward of Gondor for centuries. Boromir claimed that if the horn was heard anywhere within its borders, Gondor would come to the owner's aid.

When Boromir was slain early in The Two Towers, the Horn of Gondor was cut in two by Orcs. The horn later washed up upon the banks of the Anduin, where it was discovered by his brother, Faramir. Thus, Denethor learned of his elder son's death.