What happened 293 AD

Sometime after his return, and before 293, Diocletian transferred command of the war against Carausius from Maximian to Flavius Constantius, a former Governor of Dalmatia and a man of military experience stretching back to Aurelian's campaigns against Zenobia (272–73). He was Maximian's praetorian prefect in Gaul, and the husband to Maximian's daughter, Theodora. On 1 March 293 at Milan, Maximian gave Constantius the office of caesar.

In the spring of 293, in Philippopolis (Plovdiv, Bulgaria) or Sirmium, Diocletian gave Galerius the office of caesar, husband to Diocletian's daughter Valeria, and perhaps Diocletian's praetorian prefect.

An early instance of the partition of the Empire into East and West occurred in 293 when Emperor Diocletian created a new administrative system (the tetrarchy), to guarantee security in all endangered regions of his Empire. He associated himself with a co-emperor (Augustus), and each co-emperor then adopted a young colleague given the title of Caesar, to share in their rule and eventually to succeed the senior partner. Each tetrarch was in charge of a part of the Empire.

Qin dealt a bloody defeat to a Wei-Han alliance.