阴金鸡年 (female Iron-Rooster) 668 or 287 or −485 — to — 阳水狗年 (male Water-Dog) 669 or 288 or −484
Year 542 (DXLII) was a common year starting on Wednesday of the Julian calendar. From this year forward, the appointment of particular Roman consuls was abandoned and the office was merged with that of Byzantine emperor. Thus, the consular year dating was abandoned in practice, even though it formally remained until the end of the 9th century. The denomination 542 for this year has been used since the early medieval period, when the Anno Dominicalendar era became the prevalent method in Europe for naming years.
Lazic War – Justinian I sends a Byzantine army (30,000 men) to Armenia. The Persians, severely outnumbered, are forced to retreat, but at Dvin the Byzantines are defeated by a force of 4,000 men in an ambush, and are completely routed.[1]
Battle of Mucellium: Totila marches down into Tuscany and defeats the Byzantines at Florence, in the valley of Mugello. He treats his prisoners well, and many are induced to join his banner.