Origins
March is the war-god's month, and in the oldest stratum of the Roman calendar it was also the first month — the true New Year, when the cycle of planting and fighting began again after winter's dormancy. Its name preserves the memory of a time when Mars was not merely a god of battle but the most important deity in the agricultural and civic life of early Rome.
The Latin name 'Mārtius' is an adjective meaning 'of or belonging to Mars,' from 'Mārs' (genitive 'Mārtis'). The older form of the god's name, 'Māvors,' appears in archaic Latin texts and suggests a Proto-Italic form *Māwort-, though the ultimate etymology remains uncertain. Unlike many Roman deities, Mars has no transparent Greek equivalent in terms of name: the Greek war-god Ares bears a completely unrelated name. Mars appears to be a genuinely Italic deity whose original character was broader and more complex than the pure war-god he became in later Roman culture.
In the earliest Roman religion, Mars was an agricultural deity as much as a martial one. The 'Ambarvalia' (a ritual lustration of the fields) and the 'Suovetaurilia' (sacrifice of a pig, sheep, and bull) were performed in his honor to protect crops and livestock. His sacred animals included the wolf and the woodpecker, both creatures of the wild Italian landscape. The Salii, Mars's priestly brotherhood, performed their sacred dance and chanted the 'Carmen Saliare' — one of the oldest known Latin texts — in March, processing through Rome with the sacred shields (ancilia) that had supposedly fallen from heaven. March 1 was the most important of Mars's festival days, and it marked the beginning of the campaigning season, when the legions could march out and warfare could properly commence.
Latin Roots
The Roman calendar attributed to Romulus consisted of ten months: Mārtius, Aprīlis, Māius, Iūnius, Quīntīlis, Sextīlis, September, Octōber, November, and December. March stood first, and the numerical months that followed — Quīntīlis (fifth), Sextīlis (sixth), September (seventh), Octōber (eighth), November (ninth), December (tenth) — all counted from March. When January and February were later prepended to the calendar, these numerical names were never updated, which is why September through December are perpetually 'wrong' — named as the seventh through tenth months but occupying the ninth through twelfth positions. This numbering fossil is one of the most visible traces of March's original primacy.
The English word 'March' entered the language around 1200 CE from Anglo-Norman 'Marche,' itself from Latin 'Mārtius.' The Anglo-Saxons had their own name for this month: 'hrēþmōnaþ,' which Bede explained as the month of the goddess Hrēþe (or Rheda). Very little is known about this goddess, and some scholars suspect Bede may have been speculating. Regardless, the native name was entirely displaced by the Latin-derived form during the medieval period.
The word 'martial' (warlike, military) derives directly from 'Mārs' via Latin 'mārtiālis,' and 'Martian' (pertaining to the planet Mars) follows the same path. The planet Mars was named by the Romans for the god because of its reddish color, suggestive of blood and warfare. The phrase 'court-martial' preserves the judicial functions that the Roman Mars also oversaw, since military discipline was under his protection.
Cultural Impact
March's cultural associations are shaped by its position at the cusp of winter and spring. The phrase 'March comes in like a lion and goes out like a lamb' (or vice versa) has been proverbial in English since at least the seventeenth century, capturing the month's notorious weather volatility. In the political sphere, the 'Ides of March' (March 15) is forever associated with the assassination of Julius Caesar in 44 BCE — Shakespeare's 'Beware the Ides of March' being among the most quoted lines in English literature. The Ides were originally simply the midpoint of the month in the Roman calendar, roughly corresponding to the full moon, but Caesar's murder transformed them into a byword for betrayal and political upheaval.
In many European traditions, March 25 — the Feast of the Annunciation, also called Lady Day — served as the legal and financial New Year well into the modern period. England did not officially adopt January 1 as the start of the year until 1752, when it simultaneously adopted the Gregorian calendar. Until then, the English legal year began on March 25, a date that itself reflected the ancient association of March with new beginnings.