Arshak III,^[1] also known asArsaces III orArsak III^[2] (flourished 4th century) was anArsacid prince who served as a Roman client king ofArmenia from 378 until 387. Arshak III is often known as the last serving Roman client king of Armenia. During his reign, the part of Armenia that Arshak III governed was underRoman rule from thePeace of Acilisene.

Arshak III was the first-born son of the previous Roman client Armenian KingPap, who reigned from 370 until 374, and his wife, the Armenian noblewoman calledZarmandukht.^[3] He had a younger brother^[4] calledVagharshak. His known grandparents, both from his paternal side, were the previous ruling Arsacid monarchArshak II and his wifeParandzem.^[5]

Arshak III was the namesake of his paternal grandfather and several of hisArsacid ancestors. Arshak III was born at an unknown date during his father's reign and was raised in Armenia. Following the assassination of his father in 374, as Arshak III and his brother were too young to rule, theRoman emperorValens sent their paternal first cousinVarazdat to occupy the Armenian throne. Their cousin had lived inRome for an unknown period of time. Varazdat began his rule under the regency ofMushegh I Mamikonian, whose family was pro-Roman.

In 378, after Varazdat had his regent Mushegh Mamikonian murdered, the brother of Mushegh,Manuel Mamikonian,^[6] raised a military force which drove Varazdat out of Armenia^[7] and back to Rome. Manuel then raised Arshak III and Vologases to the throne as co-kings of Armenia, under the nominal regency of their mother Zarmandukht.^[8]

To end the political anarchy in the country, as Manuel was now the powerful regent-in-charge of Armenia, he married Arsaces III to his daughterVardandukht^[9] and Vologases to the daughter of Sahak from theBagratuni dynasty.^[10] The Mamikonian government brought peace and stability to Armenia, as Manuel guided the country wisely.^[11] Manuel treated Arshak III, Vologases and Zarmandukht with honor.^[12] He brought up Arshak III and Vologases^[13] and nurtured them as if they were his own children.^[14]

Arshak III, like his predecessors, aggressively pursued policies based onChristianArianism.^[15] In 386, Vologases died without leaving an heir and Arshak III became the sole ruler of Armenia. As Manuel Mamikonian died at the same time as Vagharshak did, the authority of Arshak III became lessened by theSassanid invasions from Persia of Armenia. In 387, the last year of his kingship, Arshak III resided in Ekeghiats (Ekeleac’), in Western Armenia,^[16] as he then ruled only Western Armenia along a line fromErzurum toMush. Around the year 390 Arshak died without leaving an heir. Western Armenia was annexed to and became a province of theByzantine Empire. Eastern Armenia was annexed by the Sassanid Empire and the subsequent ruling Arsacid monarchs in Eastern Armenia became client kings of Armenia under Sassanid rule.

• Arshak is a character in the tragedyNerses The Great, Patron of Armenia written in 1857, by the Armenian playwright, actor & editor of the 19th century, Sargis Vanandetsi, also known as Sargis Mirzayan.

• Faustus of Byzantium,History of the Armenians, 5th century
• D. M. Lang,Armenia: Cradle of Civilization – p.p. 163-165, Boston: George Allen & Unwin, 1970
• N. Lenski,Failure of Empire: Valens and the Roman State in the Fourth Century A.D., University of California Press, 2003
• R. G. Hovannisian,The Armenian People From Ancient to Modern Times, Volume I: The Dynastic Periods: From Antiquity to the Fourteenth Century, Palgrave Macmillan, 2004
• A. Terian,Patriotism And Piety In Armenian Christianity: The Early Panegyrics On Saint Gregory, St Vladimir's Seminary Press, 2005
• A. Topchyan,The Problem of the Greek Sources of Movses Xorenac’i's History of Armenia, Peeters Publishers, 2006
• V. M. Kurkjian,A History of Armenia, Indo-European Publishing, 2008
• R. P. Adalian,Historical Dictionary of Armenia, Scarecrow Press, 2010

• 4th-century kings of Armenia
• Roman client kings of Armenia
• Theodosian dynasty
• Valentinianic dynasty
• Arsacid kings of Armenia

• Articles with short description
• Short description matches Wikidata
• Date of birth not in Wikidata