A native of Pannonia, he converted to Christianity at a young age. He served in the Roman cavalry in Gaul, but left military service at some point prior to 361, when he embraced Trinitarianism and became a disciple of Hilary of Poitiers, establishing the monastery at Ligugé. He was consecrated as Bishop of Caesarodunum (Tours) in 371. As bishop, he was active in the suppression of the remnants of Gallo-Roman religion, but he opposed the violent persecution of the Priscillianist sect of ascetics.
His life was recorded by a contemporary hagiographer, Sulpicius Severus. Some of the accounts of his travels may have been interpolated into his vita to validate early sites of his cult. He is best known for the account of his using his military sword to cut his cloak in two, to give half to a beggar clad only in rags in the depth of winter.
His shrine in Tours became a famous stopping-point for pilgrims on the road to Santiago de Compostela in Spain. His cult was revived in French nationalism during the Franco-Prussian War of 1870/1, and as a consequence he was seen as a patron saint of France during the Third French Republic.
Martin was born in AD 316 or 336 in Savaria in the Diocese of Pannonia (now Szombathely, Hungary). His father was a senior officer (tribune) in the Imperial Horse Guard, a unit of the Roman army, later stationed at Ticinum (now Pavia), in northern Italy, where Martin grew up.
At the age of ten he attended the Christian church against the wishes of his parents, and became a catechumen. Christianity had been made a legal religion (in 313) in the Roman Empire. It had many more adherents in the Eastern Empire, whence it had sprung, and was concentrated in cities, brought along the trade routes by converted Jews and Greeks (the term 'pagan' literally means 'country-dweller'). Christianity was far from accepted amongst the higher echelons of society; among members of the army the worship of Mithras would have been stronger. Although the conversion of the Emperor Constantine and the subsequent programme of church-building gave a greater impetus to the spread of the religion, it was still a minority faith.
As the son of a veteran officer, Martin at fifteen was required to join a cavalry ala. At the age of 18 around 334 or 354, he was stationed at Ambianensium civitas or Samarobriva in Gaul (now Amiens, France). It is likely that he joined the Equites catafractarii Ambianenses, a heavy cavalry unit listed in the Notitia Dignitatum. As the unit was stationed at Milan and is also recorded at Trier, it is likely to have been part of the elite cavalry bodyguard of the Emperor, which accompanied him on his travels around the Empire.
According to his biographer, Sulpicius Severus, he served in the military for only another two years, though it has been argued that these two years, "are in fact not nearly enough to bring the account to the time when he would leave, that is, during his encounter with Caesar Julian (the one who has gone down in history as Julian the Apostate) Martin would have been 45 years old when Julian acceded to the throne, and at the usual end of a military contract.[clarification needed] Jacques Fontaine[year needed] thinks that the biographer was somewhat embarrassed about referring to long stint in the army, ." Such scholars[who?] as would present Martin Conscripted as the prototype of conscientious objectors hold that Martin would have remained in the army for the entirety of his prescribed twenty-five year term, and that, in their opinion, such service need not have obliged him to violate his Christian conscience by shedding blood on the battlefield.