Legio IV Scythica
Legio quarta Scythica (Fourth Scythian Legion) was a Roman legion levied by Mark Antony around 42 BC, for his campaign against the Parthian Empire, hence its other cognomen, Parthica. The legion was still active in Syria in the early 5th century. The legion's symbol was a capricorn.
In its first years, the whereabouts of IIII Scythica are uncertain, although it is probable that it took part in Antony's campaign against the Parthians. The name suggests that it fought against the Scythians. After the battle of Actium and Antony's suicide, Octavian transferred IIII Scythica to the Danube province of Moesia. The legion is reported to have taken part in civilian tasks, such as the building and keeping of roads. In his youth, future emperor Vespasian served in this legion.
Generals, Tribunes, and More 
Quintus Varius Nepos was a military tribune for Legio IIII Scythica at one point.
Campaigns in the east 
King Vologases I of Parthia invaded Armenia, a client kingdom of Rome, in 58. Nero ordered Gnaeus Domitius Corbulo, the new legate of Cappadocia, to manage the matter. Corbulo brought IIII Scythica from Moesia, and with III Gallica and VI Ferrata defeated the Parthians, restoring Tigranes VI on Armenian throne. In 62, IIII Scythica and XII Fulminata, commanded by the new legate of Cappadocia, Lucius Caesennius Paetus, were defeated by the Parthians at the Battle of Rhandeia and forced to surrender. The legions were covered with shame and removed from the war theatre to Zeugma. This city would be the base camp of IIII Scythica for the next century.
In the Year of the Four Emperors (AD69), the legion, like the rest of the Eastern army, sided with Vespasian immediately. Despite the demonstrated loyalty, IIII Scythica was not involved in actual fighting because it was not considered a high quality legion. This has to do with another defeat years earlier in the Jewish rebellion. In the 2nd century, it participated in the suppression of another Jewish rebellion, this time with more success.
Since 2nd century 
IIII Scythica participated in all campaigns of the 2nd century against the Parthian Empire. Between AD181 and AD183 the commander of the Eastern legions was Septimius Severus, who become emperor relying on the power of his legions.
The legion disappears from the sources after AD219, when their commander, Gellius Maximus, rebelled against Emperor Elagabalus and proclaimed himself emperor, only to be defeated by Elagabalus. However, according to Notitia Dignitatum, in the early 5th century, IIII Scythica was still in Syria, camped in Sura.
See also 
- Legions and Veterans: Roman Army Papers 1971-2000 By L. J. F. Keppie page 128