Fritigern (fl. 370s) was a Thervingian Gothic chieftain whose decisive victory at Adrianople during the Gothic War (376–382) led to favourable terms for the Goths when peace was made with Gratian and Theodosius I in 382.
Fritigern appears in the Latinized form Fritigernus.
The Gothic name is reconstructed as *Frithugairns "desiring peace".
The Germanized name under which Fritigern is honored in the Walhalla temple (1842) is Friediger.
The earliest references to Fritigern concern the period between
the attack on the Thervingi by Valens (367/9) and
the Hunnic raids on the Thervingi (ca. 376).
In this time, a civil war may have broken out between Fritigern and Athanaric, a prominent Therving ruler.
The conflict between Fritigern and Athanaric is mentioned by
Socrates Scholasticus, Sozomen, and Zosimus, but not by Ammianus Marcellinus and Philostorgius.
Before or during this civil war, Fritigern converted to Arian Christianity.
Athanaric's persecution of Christians mentioned by Sozomen, falls into this period.
Athanaric seems to have won this war, as he later led the Thervingi in battle against the Huns in 376.
According to Socrates, Fritigern and Athanaric were rival leaders of the (Therving) Goths. As this rivalry grew into warfare, Athanaric gained the advantage, and Fritigern asked for Roman aid. The Emperor Valens and the Thracian field army intervened, Valens and Fritigern defeated Athanaric, and Fritigern converted to Christianity, following the same teachings as Valens. Sozomen follows Socrates' account.
According to Zosimus, Athanaric (Athomaricus) was the king of the Goths (Scythians). Sometime after their victory at Adrianople, and after the accession of Theodosius, Fritigern, Alatheus, and Saphrax moved north of the Danube and defeated Athanaric, before returning south of the Danube.
In 376, the Thervings came under increasing pressure from the Huns, who had already conquered their kinsmen, the Greuthungi.
Fritigern asked Valens to allow the Thervingi to cross the northern Roman border and settle in Moesia or Thracia, with the Danube River and Roman frontier forts protecting them from the Huns.