The Byzantine army was the primary military body of the Byzantine armed forces, serving alongside the Byzantine navy. A direct descendant of the Roman army, the Byzantine army maintained a similar level of discipline, strategic prowess and organization. It was among the most effective armies of western Eurasia for much of the Middle Ages.The early Byzantine army received a mixed diet of victory and defeat - consequently the cavalry arm became more prominent as the legion system disappeared in the early 7th century. Later reforms reflected some Germanic and Asian influences - with every encounter against a ferocious opponent the Byzantines would find a new source of excellent mercenaries with Huns, Cumans, Alans and (following the Battle of Manzikert) Turks meeting the Empire's appetite for light cavalry mercenaries. Since much of the Byzantine military focused on the strategy and skill of generals utilizing militia troops, heavy infantry were recruited from Frankish and later Varangian mercenaries.

John I Tzimiskes or Tzimisces, (Greek: Ιωάννης Α΄ Τζιμισκής, Iōannēs I Tzimiskēs; Armenian: Հովհաննես Ա Չմշկիկ Hovhannes A Čmškik, Armenian pronunciation: [hovɑˈnɛs tʃʰəməʃˈkik]; circa 925 – January 10, 976) was Byzantine Emperor from December 11, 969 to January 10, 976. A brilliant and intuitive general, John's short reign saw the expansion of the Empire's borders and the strengthening of Byzantium itself.

John was born into the Kourkouas clan, a family of Armenian origin. Scholars have speculated that his nickname "Tzimiskes" was derived either from the Armenian Chmushkik, meaning "red boot", or from an Armenian word for "short stature." A more favorable explanation is offered by the medieval Armenian historian Matthew of Edessa, who states that "Tzimiskes was from the region of Khozan, from the area which is now called Chmushkatzag." Khozan was located in the region of Paghnatun, in the Byzantine province of Fourth Armenia (Sophene).

Tzimiskes was born sometime in 925 to an unnamed member of the Kourkouas family by the sister of the future Emperor Nikephoros II Phokas. Both the Kourkouai and the Phokadai were distinguished Cappadocian families, and among the most prominent of the emerging military aristocracy of Asia Minor. Several of their members had served as prominent army generals, most notably the great John Kourkouas, who conquered Melitene and much of Armenia.