Being Emperor of Rome was the most powerful position in the ancient world. Mostly, Rome's best kown great rulers are figures like Augustus or crazy tyrants like Caligula. However, the Roman Empire had a lot of Emperors. A select few of them had very short rules. This will look at the five shortest ruling emperors of the Principate Period (30 BC-284 AD).
The rise and fall of these short ruling emperors
Otho's rise to power started after the ambitious noble was forced to divorce his wife so she could be with Emperor Nero (37-68). This caused him to join up with Galba (3 BC-69 AD) to overthrow Nero, which led to Galba becoming emperor. Seven months into Emperor Galba's rule, Otho decided he wanted to become emperor. To do this he payed off the Praetorian Guard, who served as the emperor's security detail and secret police. They then assassinated Galba and his adopted son and proclaimed heir to the throne Lucius Piso Licinianus (38-69).
Otho then became emperor, but he soon learned of a uprising after reading Galba's private correspondences. He discovered several legions in Germany had declared allegiance to Vitellius (15-69) and proclaimed him emperor. They were marching to Italy to overthrow who they thought was Emperor Galba. Otho rallied an army, but Vitellius and his commanders forced the decisive First Battle of Bedriacum, which they won. Upon receiving this news Otho committed suicide. It is assumed that he killed himself to prevent the country from going into civil war, even though he still had a formidable army at his side.
Pertinax came from humble beginnings, having been born the son of a freed slave and working as a teacher. He then joined the army and became an officer. He then moved up to become a provincial governor and later a member of the Roman Senate.
By 192, people were sick of Emperor Commodus (161-192) straining the Roman economy with his gladiatorial fights and his bouts of megalomania. This led to his assassination on New Year's Eve. He was strangled to death by his wresting partner when he was taking bath after a failed poisoning attempt. Following Commodus's death, which Pertinax may have been involved in as a co-conspirator, he was made emperor.
In one of his first acts as emperor, Pertinax made the mistake of ticking off the Praetorian Guard by wanting to reform them from their pampered lifestyle. This soon resulted in about 300 Praetorian Guard members storming the gates of his palace, meeting no resistance. However, Pertinax did not flee and tried to reason with 300 armed, unhappy soldiers. He almost succeeded in doing so, but was assassinated.
Didius Julianus (133/37-193)
Following Pertinax's assassination, the Praetorian Guard decided to auction off the position of Emperor to the highest bidder. Pertinax's father-in-law and prefect of Rome, Titus Flavius Cladius Sulpicinaus (ca. 137-197) showed up to make an offer. Didius Julianus also showed up after being told about what was happening while at a banquet with his family. Julianus was born into a prominent family, raised by Emperor Marcus Aurelius's mother and received public distinction at an early age.
Julianus won the action by offering the Praetorian Guard 25,000 sesterces (8 years worth of wages) and then was made emperor by the senate under military threat. His time as Emperor was not well received, as the people were unhappy with how he "earned" the position. The people of Rome greeted him with groans, shouts and even threw stones at him.
Soon generals in Syria, Pannonia and Britain refused to recognize Julianus as emperor. Septimius Severus (145-211) in Pannonia led an army that crushed any attempts by Julianus to stop him. He even flipped the Praetorian Guard to his side if they gave up Pertinax's murders. Julianus's last ditch efforts at negotiation failed and he ended up being murdered in his own palace.
Gordian I (c.159-238) and Gordian II (c.192-238)
Goridan I climbed up the political system to become a Roman Senator and governor of Britain. In 237, he became proconsular governor of the province of Africa Proconsularis and brought his son Gordian II to be his general. During this time Maximinus Thrax (173-238) had been emperor for about three years. He was a ruthless leader and hated the nobility. In 238, there was a revolt in Africa after the procurator Thrax installed was killed in a riot because of higher taxes and fines.
The rebels then asked Goridan I to become Emperor, since he was well liked and respected. Goridan declined at first sighting his advanced age (79). However, he eventually gave in on the condition that his son Gordian II would become joint Emperor with him. Gordian then sent an embassy to the Senate in Rome. The Senate, who hated Thrax, confirmed him and his son as joint Emperors.
Most of the provinces sided with Gordian, but the governor of the neighboring province of Numidia was a loyal Thrax supporter. Capelianus also hated Gordian and managed to have the only Roman legion in the area. His legion went against Goridan II and his militia of untrained men at the Battle of Carthage. Gordian II died in battle and Gordian I hung himself upon receiving the news. In the end, Thrax was assassinated by his own troops during the Siege of Aquileia. This led to Pupienus (c.165/170-238) and Balbinus (c.178-238) becoming joint emperors with Gordian III (225-244) holding power nominally due the fact that he was only 13.
Effects on the Roman Empire
Each of these emperors came to power during very unstable period of the Rome Empire in which their was civil war and dynasty transition. Otho ruled during the Year of the Four Emperors during the transition from the Julio-Claudians dynasty (27 BC - 68 AD) to the Flavian dynasty (69-96). Pertinax and Didius Julianus came to power during the Year of the Five Emperors. This was during the transition from the Nerva-Antonine dynasty (96-192) to the Severan dynasty (193-235). Lastly, the Gordians reigned during the Year of the Six Emperors. This happened shortly after the start of the the Barracks Emperors period (235-284) and would end with the Gordian dynasty (238-244).