"... the hosts of Mordor wailed, and terror took them, and they fled, and died, and the hoofs of wrath rode over them. And then all the host of Rohan burst into song, and they sang as they slew, for the joy of battle was upon them, and the sound of their singing that was fair and terrible came even to the City [Minas Tirith]."
—The Return of the King
The Rohirrim are most well-known in Middle-earth for their cavalry and horse training. The landscape of Rohan was well-suited for these types of activities, with massive "seas of grass" for riding and grazing. Horsemen formed the bulk of their military and were used effectively in many battles, including the Hornburg and the Pelennor Fields.