Legio quarta Scythica ("Scythian Fourth Legion") was a legion of the Imperial Roman army founded c. 42 BC by the general Mark Antony, for his campaign against the Parthian Empire, hence its other cognomen, Parthica. The legion was still active in Syria in the early 5th century.
In its first years, the whereabouts of IV 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 IV 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.
King Vologases I of Parthia invaded Armenia, a client kingdom of Rome, in 58, beginning the Roman–Parthian War of 58–63. 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, in 69, the legion, like the rest of the Eastern army, sided with Vespasian immediately. Despite the demonstrated loyalty, IV 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.
The legion took part in the war against the Parthians between 161 and 166. Between AD 181 and 183 Septimius Severus acted as the commander of the Eastern legions, and he later relied on the power of said legions to become emperor.
The Legion's former commander, now Emperor, led another campaign against the Parthians.
The legion disappears from the sources after AD219, when their commander, Gellius Maximus, rebelled against Emperor Elagabalus and proclaimed himself emperor, but was defeated by Elagabalus.
However, according to Notitia Dignitatum (XXXIII), in the early 5th century, IIII Scythica was still in Syria, camped in Orese.
Quintus Varius Nepos was a military tribune for Legio IV Scythica at one point.
The legion's symbol was a capricorn.
The Legion appeared in Harry Sidebottom's historical fiction series Warrior Of Rome.