Mars: Roman God of War, Agriculture, and the Founding of Rome

Mars was the second most important god in Roman religion, behind only Jupiter. He was the god of war, the divine father of Romulus, and the patron of the Roman military. He was also, in his oldest form, a god of agriculture and the protection of fields — a combination that surprises modern readers but made complete sense in the Roman world, where the survival of the community depended on both a productive harvest and the ability to defend it.

His name gives us the month of March, the planet Mars, the French word mardi (Tuesday), and the English word “martial.” He was the Roman counterpart of the Greek Ares, but the two gods had substantially different characters. Ares was generally portrayed in Greek literature as violent, impulsive, and not particularly admired even by the other gods. Mars was one of Rome’s most respected and deeply honored deities — a god whose worship was woven into the structure of the Roman year, the Roman military, and Roman identity itself.

Mars Before War

Mars was one of the oldest deities in the Italic religious world, and his original domain was not war but the protection of agricultural communities from threats — both natural and human.

The oldest Roman calendar, traditionally attributed to Romulus, began with March as its first month. This was Mars’s month, and the timing was agricultural: March marked the beginning of the growing season in central Italy, the moment when winter ended, fields could be plowed, and animals could be put out to graze. It also marked the beginning of the campaigning season, when armies could move again after winter. Both activities — farming and fighting — started in March, under Mars’s patronage.

The prayer of the Arval Brethren (AR·val) — an ancient priestly college dedicated to agricultural fertility — invoked Mars alongside the household gods and the Lares for the protection of fields, crops, and cattle. This is Mars before he became primarily a war god: a powerful protective deity whose force was directed at keeping the community and its food supply safe from whatever threatened them.

As Rome expanded and warfare became increasingly central to Roman identity and economy, Mars’s war aspect grew dominant. But the agricultural layer never disappeared entirely. His festivals in March and October bracketed the military season — March opening it, October closing it — while also marking the agricultural year. The same rituals that sent armies out in spring and purified their weapons in autumn also blessed the fields.

Mars and the Founding of Rome

Mars’s most important mythological role was as the father of Romulus and Remus, which made him the divine ancestor of the Roman people.

The story began with Rhea Silvia (REE·a SIL·vi·a), a Vestal Virgin and princess of Alba Longa. Her uncle Amulius had seized power from her father Numitor and forced Rhea Silvia into the Vestal order to prevent her from producing heirs who might challenge him. Mars, according to the myth, came to her while she slept in his sacred grove and fathered the twins.

When Amulius discovered the pregnancy he had the twins exposed — left on the banks of the Tiber to die. They survived, suckled by a she-wolf in the cave called the Lupercal at the foot of the Palatine Hill, then raised by a shepherd named Faustulus. When they grew to adulthood they overthrew Amulius, restored Numitor, and founded Rome.

The theological implication was direct and deliberate: Rome was a city founded by the son of a god. Not just any god — Mars, the divine force of military power and protection. Roman identity was therefore not merely human. It was divinely authored, militarily guaranteed, and backed by the most important war god in the pantheon.

Augustus, who used this mythology extensively in his political program, emphasized his own descent from Venus through Aeneas while simultaneously honoring Mars as the father of Rome’s founder. The Temple of Mars Ultor that he built in his forum was partly a theological statement: the god who fathered Rome had now avenged Caesar’s murder through Augustus’s victory over his assassins.

The Salii and the Sacred Shields

The most visually dramatic aspect of Mars’s worship was the Salii (SAH·lee·ee) — the dancing priests of Mars who processed through Rome throughout the month of March.

The Salii were a college of twelve priests, drawn from patrician families, who dressed in full archaic military armor: breastplate, bronze helmet, short sword, and the distinctive trabea, a striped military cloak. Each carried one of the twelve sacred shields called ancilia (an·SIL·ee·a) — oval shields with curved notches cut into their sides — and a staff with which they struck the shields rhythmically as they danced.

The origin myth of the ancilia was that one shield had fallen from heaven during the reign of Numa Pompilius, the second king of Rome, accompanied by a divine declaration that Rome would be supreme as long as it possessed the shield. To prevent it from being stolen or lost, Numa had eleven identical copies made, so that no one could tell the original from the replicas.

Throughout March the Salii processed through Rome’s streets in elaborate, formally prescribed dance movements called the tripudium (tri·POO·dee·um) — a three-beat stamping dance — singing the Carmen Saliare, one of the oldest surviving texts in the Latin language, so archaic that even Romans of the classical period could not fully understand it. They stopped at specific points in the city to perform their rites, ate elaborate ritual dinners at public expense, and resumed the next day.

The Salii were not a marginal or occasional priesthood. They were one of Rome’s oldest and most prestigious priestly colleges, and their March ceremonies were among the most elaborate ritual events in the Roman religious calendar. For the entire month, certain civic activities — including marriages and the departure of armies — were considered inappropriate or unlucky, because the month belonged to Mars and his priests.

A second college of Salii, associated with the Quirinal Hill rather than the Palatine, performed similar ceremonies in October, marking the close of the military season and the ritual purification and storage of weapons until the following spring.

The Campus Martius

The Campus Martius (KAM·pus MAR·shus) — the Field of Mars — was one of the most important spaces in Roman life, and its name expressed its dedication to the god who governed what happened there.

The Campus was a flat plain along the bend of the Tiber River, outside the original boundary of the city (pomerium). This location was significant: military activities could not take place inside the pomerium without special authorization, because war belonged to the space outside the city’s sacred boundary. The Campus Martius was where that boundary ended and Mars’s domain began.

It was where Roman armies assembled before campaigns and were reviewed by their commanders. It was where the census was held — the counting and classification of Roman citizens that determined military obligation and political rights. It was where young men trained and where the comitia centuriata, the most important popular assembly for military and political decisions, convened.

Augustus transformed the Campus Martius into one of Rome’s most architecturally magnificent districts, building his mausoleum, the Ara Pacis (Altar of Peace), the Horologium (a giant sundial using an Egyptian obelisk as its gnomon), and the Pantheon there. By developing the Field of Mars as a showcase of Augustan achievement, he connected his political program directly to the divine patron of Rome’s military greatness.

Mars’s Epithets

Mars’s many official titles reflect the range of functions his worship served.

Mars Gradivus (gra·DEE·vus) — the Striding Mars, or Mars who makes armies advance — was the aspect invoked before battle. His temple stood outside the Porta Capena, the gate through which armies departed Rome on campaign. Generals gathered their troops there before marching out and made offerings to secure his support.

Mars Ultor — the Avenger — was the epithet under which Augustus built his most famous temple to Mars in the Forum of Augustus. Augustus had vowed the temple before the Battle of Philippi in 42 BCE, where he and Mark Antony defeated Brutus and Cassius, the assassins of Julius Caesar. The vow was that if he won he would build Mars a temple in gratitude for divine assistance in avenging Caesar’s murder. The temple, completed in 2 BCE, housed the standards that had been lost by Crassus at the Battle of Carrhae in 53 BCE and recovered by diplomatic negotiation with Parthia — another act of restoration and vengeance that Augustus associated with Mars Ultor.

Mars Pater — Father Mars — was the form addressed in agricultural prayers, particularly in the prayer of the Arval Brethren, where Mars was asked to protect crops, livestock, and farmhands from disease, bad weather, and harm.

Mars Silvanus connected him to the god of forests and wild places, expressing Mars’s protective role extended to the boundary between cultivated land and wilderness.

The Myths of Mars

Mars’s mythology is less extensive than Apollo’s or Bacchus’s, partly because his Roman identity was more institutional than literary. He appeared in myths primarily in his foundational role as father of Romulus and in his love affair with Venus.

The affair with Venus was one of the most famous stories in Roman mythology, told at length by Ovid and alluded to throughout Latin literature. Mars and Venus, the divine embodiments of war and love, were lovers — a union that Roman thinkers found philosophically significant, since it expressed the idea that conflict and harmony are not opposites but complements, each requiring the other.

Vulcan, Venus’s husband, discovered the affair and responded with characteristic ingenuity. He forged an invisible net of extraordinary fineness, spread it over the marriage bed, and then announced he was leaving for a trip. Mars and Venus, believing themselves alone, were caught when the net snapped shut around them. Vulcan called the other gods to witness the entrapment. Some laughed. Others, according to Ovid, quietly expressed that they wouldn’t mind being caught in the same position. The episode ended with Neptune persuading Vulcan to release the captives in exchange for a guarantee of compensation.

The myth was often read as a comedy of divine manners, but it also made a serious point: even the most disciplined and powerful of the gods — Mars, who embodied military order and control — was subject to desire and its consequences.

The October Horse

The October Equus — the October Horse — was one of the strangest and most ancient of Mars’s rituals, performed on the Ides of October to mark the close of the military season.

A horse race was held on the Campus Martius. The right-hand horse of the winning team was immediately sacrificed to Mars. Its head was cut off and decorated with a garland of bread, then became the object of a ritual contest between two neighborhoods of Rome — the Via Sacra neighborhood and the Subura neighborhood — who fought to claim and display it. The tail was carried at a run to the Regia, the ancient royal house in the Forum, and the blood dripped onto the sacred hearth there before it could coagulate.

The ritual is old enough that its full meaning was obscure even to ancient Romans who commented on it. The most plausible interpretation connects it to the purification of the military season: the horse, as a military animal, was sacrificed to Mars at the end of the campaign year, the blood dedicated to the hearth of Rome, the head contested between neighborhoods as a marker of community vigor and competition. The ritual closed the military season as the Salii’s October ceremonies purified the weapons, ending Mars’s active year until March brought him back.

Mars and Augustus

No Roman ruler used Mars more deliberately or effectively than Augustus.

After the assassination of Julius Caesar, Augustus fought a long series of civil wars before establishing the Principate. Throughout this period he positioned himself as the avenger of Caesar’s murder, the restorer of Roman order, and the instrument of Mars’s justice. The Temple of Mars Ultor was the physical expression of this positioning — a magnificent building in a magnificent forum, housing the sacred standards recovered from Parthia, decorated with representations of Aeneas and Romulus as the two divine and semi-divine founders of the Roman line that led to Augustus himself.

The Ara Pacis — the Altar of Peace — dedicated in 9 BCE on the Campus Martius, showed Augustus’s program from the other side: having established peace through Mars’s military support, he now governed a world at rest. The altar’s imagery included a panel showing Mars himself watching over the figures of Romulus and Remus with the she-wolf, directly connecting the founding myth to Augustan ideology.

Augustus was careful not to claim personal identification with Mars — that would have been the kind of divine arrogance that Romans found distasteful. Instead he positioned himself as Mars’s instrument, the man through whom the god of war had accomplished his will for Rome. The distinction was theologically important and politically effective.

Symbols and Sacred Things

Mars’s spear, kept in the Regia — the ancient house of the kings near the Forum — was one of Rome’s most sacred objects. When it was seen to move on its own, Romans interpreted this as a sign that Mars was signaling war. Generals about to depart on campaigns went to the Regia to touch the spear and call on Mars, saying Mars vigila — Mars, be watchful.

The wolf was his sacred animal, connected to the founding myth through the she-wolf who nursed Romulus and Remus. The woodpecker (picus) was also sacred to him — a bird associated in Italic religion with prophetic knowledge and divine guidance, often depicted accompanying Mars in his older agricultural aspect.

Red was his color, expressing blood, vitality, and the heat of battle. Roman generals wore red cloaks. The planet Mars, which appears distinctly red in the night sky, carried his name for this reason.

His month — March — was named directly for him, as was Tuesday in the Romance languages: French mardi, Spanish martes, Italian martedì, all from Latin Martis dies, the day of Mars.

Mars’s Place in Roman Religion

Mars occupied a position in Roman religion that no Greek deity quite paralleled. He was second in the divine hierarchy after Jupiter, but unlike Jupiter — whose authority was cosmic and civic — Mars’s authority was specifically Roman. He was not a universal war god in the way Jupiter was a universal sky god. He was Rome’s war god, the divine patron of Rome’s specific military identity.

This specificity made him more personally meaningful to Roman soldiers, farmers, and citizens than a more abstract deity might have been. He had fathered their founder, protected their fields, accompanied their armies, and received their spoils. He was present at every stage of the military year through formal ritual, and his priests processed through their streets every March.

The Roman army was the most effective military force in the ancient world for several centuries. The Romans understood this not as a matter of tactics or equipment alone — though they were serious about both — but as evidence of divine favor. Mars’s support for Rome was not assumed but actively maintained through sacrifice, ritual, proper conduct of warfare, and the dedication of spoils. To fight well was to honor Mars. To honor Mars was to fight well. The two were inseparable.

Final Take: Mars

Mars mattered to Rome in a way that went beyond military theology. He was present at the beginning of Rome’s story, as the father of its founder. He was present at the beginning of every Roman year, as the god whose month opened the calendar. He was present at the beginning of every campaign season, as the god whose priests danced through the streets in armor and whose spear was touched by departing generals.

He represented something Rome genuinely believed about itself: that its military power was not accidental or purely human. It was divinely sanctioned, divinely assisted, and divinely accountable. When Rome fought justly, Mars stood behind it. When it fought unjustly — or so the theology implied — it could not rely on his support.

That accountability gave Roman military culture a moral dimension that pure power-worship would not have produced. Mars was not simply the god of winning. He was the god of fighting rightly, and the Romans understood the difference.

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