Ulpius Cornelius Laelianus is one of the third century "gallic emperors" and usurpers about which history has little real knowledge. What is known about Laelianus has been mostly from his coins. Because of his short reign there was little time for him to make much of a mark on history. His coins, however, are much sought after for their rarity. Laelianus date of birth and his origin are unknown and most literary sources have his name wrong. Only one of the earliest of his coins gives his full name as ULPIUS CORNELIUS LAELIANUS.
Laelianus shared the same nomen as a prominent Spanish noble family, the Ulpii, that included Trajan among its members, and may have been a relative. This is supported by the strong allusion to Spain on an aureus he struck, which featured the design of Hispania reclining with a rabbit to her side. If he indeed was a relative, this may be the reason Spain allied itself with Claudius II, after the death of Postumus, seemingly without a struggle.
Laeilianus was an usurper against Postumus, himself another usurper, who was unable to rout the incumbent when their forces met in battle. Laelianus thus had a tenure lasting from near the beginning of the year 269 through no later than that summer. Although his exact position is unknown, he is believed to have been a senior officer under Postumus. Laelianus represented a strong danger to Postumus because he was believed to be governor of Germania Superior and therefore had the command of two legions. (Legio XXII Primigenia, Legio VIII Augusta at Argentorate -Strasbourg-).
It is possible that Laelianus' usurpation took place after a successful military campaign against Germanic invaders, which the Historia Augusta attributes to his reign. The literary sources do not indicate the exact beginning or end of Laelianus' usurpation, but most likely he rebelled against Postumus in February or March of 269 A.D. Judging from the number of coins which were issued in his name, Laelianus' rebellion can be estimated to have lasted for two to three months at the most before he was executed by his own soldier. The siege of Mainz was also fatal for Postumus; it is said he was slain when he refused to allow his troops to plunder the city following its capture.