Kingdom of Soissons

The Kingdom or Domain of Soissons is the historiographical name for the de facto independent Roman remnant of the Diocese of Gaul, which existed during late antiquity as a rump state of the Western Roman Empire until its conquest by the Franks in AD 486. Its capital was at Noviodunum, today the town of Soissons in France.

The rulers of the rump state, notably its final ruler Syagrius, were referred to as "kings of the Romans" (Latin: rex Romanorum) by the Germanic peoples surrounding Soissons, with the polity itself being identified as the Regnum Romanorum, "Kingdom of the Romans", by the Gallo-Roman historian Gregory of Tours. Whether the title of king was used by Syagrius himself or was applied to him by the barbarians surrounding his realm (in a similar way to how they referred to their own leaders as kings) is unknown. However, it is most likely that they never referred to their leaders as kings because the Romans saw the word "king" or Rex in Latin as taboo because of its association with the tyrannical early Roman kings.

The emergence of a visibly autonomous Roman polity based around Noviodunum can be traced back to the appointment of Aegidius as magister militum of Roman Gaul by Emperor Majorian. When Majorian was killed on the orders of Ricimer in 461, Aegidius maintained his own power in the remnants of Roman Gaul against Franks to his east and Visigoths to his south.

Aegidius died in 464 or 465. His son Syagrius succeeded to the rule. In 486, Syagrius lost the Battle of Soissons to the Frankish king Clovis I and the domain was thereafter under the control of the Franks.