The Ides of October marked the end of the campaigning season, and on that day a race was held on the grassy sward of the Campus Martius, just outside the Servian Walls of Republican Rome.

The year’s best war horses were harnessed in pairs to chariots and driven at breakneck pace; the right-hand one of the winning pair became the October Horse, and was ritually killed with a spear by the flamen Martialis, the special priest of Mars, who was god of war. Then the October Horse’s head and genitalia were amputated. The genitals were rushed to bleed on the sacred hearth in the Regia, Rome’s oldest temple, after which they were given to the Vestal Virgins to burn to ashes in the sacred flame of Vesta; later these ashes were mixed into cakes offered on the anniversary of the founding of Rome by her first king, Romulus. The decorated head was tossed into the midst of two teams of humble citizens, one from the Subura district, one from the Sacra Via district, who fought strenuously for possession of it. If the Subura won, the head was nailed to the Turris Mamilia. If the Sacra Via won, the head was nailed to an outer wall of the Regia.

In this ritual so old that no one remembered how it had begun, the very best that Rome owned was sacrificed to the twin powers that ruled her: war and land. Out of them came her might, her prosperity, her everlasting glory. The death of the October Horse was at once a mourning of the past and a vision of the future.