The Byzantine catepan of Italy, Michael Doukeianos, moved from Bari with the few troops he could muster, including some Varangians, troops from the Opsikion tagma and several Thracians.
John's namesake grandfather had been a commander of the elite Hikanatoi regiment (tagma) under Emperor Basil I (reigned 867–886); John's brother Theophilos became a senior general, as did John's own son, Romanos, and his great-nephew, John Tzimiskes.
In 1087 he commanded the Byzantine right wing in the Battle of Dristra against the Pechenegs, and in 1090 he defeated a small force of 300 Pechenegs while leading the Archontopouloi tagma against them.