The Timpson Lyceum · History of Rome – Titus Livius (2025)

Tullus Hostilius, Third King of Rome– Lecture 4 (History of Rome)

Overview

Tullus Hostilius, the third king of Rome (traditionally reigning 673–642 BC), is Livy's deliberate mirror-image of his predecessor. Where Numa Pompilius had given Rome two generations of peace and religion, Tullus was restlessly warlike — more warlike even than Romulus, in Livy's judgment. Grandson of the warrior Hostus Hostilius, who had fallen fighting the Sabines under Romulus, Tullus set out to drag Rome back to a conquering culture and treated Numa's religious apparatus as a waste of time.

His reign matters because it stages Rome's first great act of consolidation: the war with Alba Longa, the mother-city of the Latin people, settled by champion combat — the Horatii against the Curiatii — and ended by Alba's outright destruction and the absorption of its population into Rome. That single act roughly doubled Rome's manpower, added a hundred noble Alban families to the Senate, and set the pattern Rome would follow for centuries: defeat a neighbor, then swallow it whole rather than merely tax it. Tullus' end is equally instructive about the Roman mind — struck down (by plague, or by Jupiter's lightning for botched rites) after a life spent scorning the gods.

Key Concepts

• Tullus Hostilius (r. 673–642 BC) — Third king of Rome, ruling 32 years. An expansionist who consciously modeled himself on Romulus, not Numa. His grandfather Hostus Hostilius had been a celebrated soldier in Romulus' Sabine wars, and Tullus aimed to restore that martial spirit.
• Alba Longa — Capital of the Latins, set in the Alban Hills above the Alban Lake, and by tradition the city Rome itself descended from (founded by Ascanius, son of Aeneas). Rome was originally one Latin community among many; the war with Alba is therefore a war among kin, not against foreigners.
• The cattle-raid casus belli — War broke out over a trivial dispute between farmers on each side over stolen cattle, with both kings eager for any excuse to expand. Each dispatched envoys demanding restitution; each intended war regardless.
• Mettius Fufetius — The Alban dictator, appointed when their king died on campaign. Facing Tullus, he argued that a full battle would leave the victor too weakened to resist the Etruscans looming to the north — a lose-lose — and so proposed settling the war by champion combat.
• The Horatii and Curiatii — Two sets of triplets, the Horatii for Rome and the Curiatii for Alba, chosen to fight as proxies for their whole armies: the losers' city would submit to the winners'. The lone surviving Horatius won by separating three wounded opponents and defeating them one at a time.
• Champion combat (proxy battle) — Settling a war by a small duel "as if it were the whole army." It caps casualties and spares both sides the exhaustion that would invite a third party to pick them off.
• The betrayal at Fidenae — When Fidenae and Veii revolted (incited by resentful Albans), Mettius marched his Alban contingent off the field mid-battle, planning to join the winner. Tullus calmed his own men by claiming it was a planned maneuver; the ruse held the Roman line and panicked the rebels into flight.
• The execution of Mettius Fufetius — For his treachery Mettius was torn apart between two chariots driven in opposite directions — Rome's first and most notorious act of judicial dismemberment, a punishment fitting a "divided" mind.
• Destruction of Alba Longa — Tullus razed the city and transplanted its whole population to Rome, settling many on the Caelian Hill. Its leading families were enrolled in the Senate.
• Enlargement of the Senate to 300 — One hundred prominent Alban families were added, and Rome's fighting strength roughly doubled to about 6,000 infantry and 600 cavalry.
• The Tullianum — Rome's oldest dungeon, the lower chamber of the Carcer beside the Forum, whose name Roman tradition linked to Tullus. A cramped underground cell where enemies of the state were held and executed.
• The death of Tullus — A plague struck late in his reign. The scorner of ritual turned frantically superstitious, attempting rites to Jupiter Elicius; performing them wrongly, he was (by the memorable tradition) destroyed by a thunderbolt — punished for both his neglect and his clumsy piety.
• Livy's living memorials — Romans of Livy's own day (six centuries later) could still point to markers in the fields where the Horatii and Curiatii fell — a measure of how deeply Romans wove their legendary history into the landscape.

Worked Example

Why a 3-vs-3 duel beat a pitched battle — and how one man beat three.

Set the war of Rome against Alba Longa (traditionally c. 667 BC, within Tullus' reign that runs from $673$ to $642$ BC) as a decision problem. Each side fields roughly the army Rome would soon possess: about $6{,}000$ men.

1. Cost of a full battle. Even a moderate engagement costs the winner around $10\%$ and the loser around $30\%$ of their men. Total dead:

$0.10 \times 6000 + 0.30 \times 6000 = 600 + 1800 = 2400.$

1. Cost of a champion duel. At most the six triplets die:

$\text{max deaths} = 3 + 3 = 6.$

1. The ratio that made the choice obvious. The proxy fight is cheaper by

$\frac{2400}{6} = 400\times,$

and — decisively — neither surviving army is weakened, so the watching Etruscans gain nothing. Both kings preferred a $3\times3$ gamble to a $6000\times6000$ bloodletting.

1. The tactical problem inside the duel. Early on, two Horatii fell, but all three Curiatii were wounded — in different degrees — while the last Horatius was untouched. Facing three foes at once is near-suicidal. Suppose each still-standing opponent lands a disabling blow in a given exchange with probability $a = 0.2$. Fighting all three simultaneously, the chance he is hit in one round is

$1 - (1 - 0.2)^3 = 1 - 0.512 = 0.488,$

almost a coin-flip every round.

1. Separation changes the arithmetic. By feigning flight, the unwounded Horatius drew the wounded men into a strung-out pursuit, so he met them one at a time. Against a single opponent the per-round danger drops to

$a = 0.2,$

less than half the $0.488$ he faced against the trio.

1. Winning all three. Treating the three sequential duels as independent, with a high single-duel win probability $p = 0.85$ (he is fresh; they are wounded and tiring), his chance to sweep all three is

$p^3 = 0.85^3 \approx 0.61,$

versus a far smaller chance in a simultaneous 3-on-1. The most wounded Curiatius, reached last and exhausted, "barely put up a fight." By converting one $1$-vs-$3$ into three $1$-vs-$1$ contests, Horatius turned a near-certain death into a better-than-even victory — and won Rome the mastery of Alba. $\blacksquare$

Summary

• Tullus Hostilius (r. 673–642 BC, ~32 years) reversed Numa's pacifism, restoring Rome to a conquering, warrior culture.
• The war with Alba Longa, Rome's own mother-city, was settled by the champion combat of the Horatii vs. the Curiatii, won when the lone surviving Horatius separated three wounded foes and killed them one by one.
• The Alban dictator Mettius Fufetius betrayed Rome at Fidenae and was torn apart by chariots; Tullus then razed Alba Longa and moved its people into Rome.
• Absorbing Alba added 100 families to the Senate (bringing it to 300) and roughly doubled Rome's army to about 6,000 foot and 600 horse — the template of conquest-by-incorporation.
• Tullus, lifelong scorner of ritual, turned superstitious in a plague and (by tradition) was killed by Jupiter's lightning for performing the rites wrongly; his name survives in the Tullianum, Rome's oldest prison.