While the Decius himself may have intended the edict as a way to reaffirm his conservative vision of the Pax Romana and to reassure Rome's citizens that the empire was still secure, it nevertheless sparked a " terrible crisis of authority as various Christian bishops and their flocks reacted to it in different ways.

The story of Decius as preserved has been patterned after that of the military tribune of 258, but Decius could still have performed some heroic act in 343, the memory of which became the origin of the later embellished tale.

Decius is the sole surviving member of his family ( or at least the only member still in the Senate ), since his family connection with Caesar has separated him from the rest of his family, who were disgraced and destroyed for their support of Pompey.

First, Decius ' predecessor Philip the Arab had refused to continue payments, initiated by Emperor Maximinus Thrax in 238, of annual subsidies to the aggressive tribes of the region.

Decius may also have taken with him troops from the Danube frontier, in order to depose Philip in 249.

* Emperor Philip the Arab entrusts Trajan Decius with an important command on the Danube.

* The revolts of Pacatianus in Moesia and Iotapianus in Syria are put down by senator Decius, by order of emperor Philip the Arab.

Unlike some of his immediate imperial predecessors such as Philip the Arab or Maximinus who did not have extensive administrative experience before assuming the throne, Decius was a distinguished senator who had served as consul in 232, had been governor of Moesia and Germania Inferior soon afterwards, served as governor of Hispania Tarraconensis between 235 – 238, and was urban prefect of Rome during the early reign of Emperor Philip the Arab ( Marcus Iulius Phillipus ).

Around 245, Emperor Philip entrusted Decius with an important command on the Danube.

By the end of 248 or 249, Decius was sent to quell the revolt of Pacatianus and his troops in Moesia and Pannonia ; the soldiers were enraged because of the peace treaty signed between Philip and the Sassanids.

Philip was overthrown and killed following a rebellion led by his successor Decius.

Overwhelmed by the number of invasions and usurpers, Philip offered to resign, but the Senate decided to throw its support behind the Emperor, with a certain Gaius Messius Quintus Decius most vocal of all the senators.

Philip was so impressed by his support that he dispatched Decius to the region with a special command encompassing all of the Pannonian and Moesian provinces.

Although Decius tried to come to terms with Philip, Philip's army met the usurper near modern Verona that summer.

Decius won the battle and Philip was killed sometime in September 249, either in the fighting or assassinated by his own soldiers who were eager to please the new ruler.

Herennius was very close to his father and accompanied him in 248, as a military tribune, when Decius was appointed by Philip the Arab to deal with the revolt of Pacatianus in the Danube frontier.

Acclaimed emperor by his own troops, Decius marched into Italy and defeated Philip near modern Verona.

A section covering the reigns of Philip the Arab, Decius, Trebonianus Gallus, Aemilian and all but the end of the reign of Valerian is missing in all the manuscripts, and it has been argued that biographies of Nerva and Trajan have also been lost at the beginning of the work, which may suggest the compilation might have been a direct continuation of Suetonius.

As the coin was dated to Philip the Arab age, it is possible he revolted against Philip, with his revolt ending under Emperor Decius, since Eutropius ( ix. 4 ) reports of a bellum civile suppressed in Gaul during this emperor rule.

According to Zosimus, the revolts of Pacatianus in Moesia ( he probably controlled Viminacium ) and Iotapianus in Syria prompted Philip to make an offer to the Roman Senate to step down, but the senator Decius ( who was sent by Philip to deal with the rebellion ), correctly predicted that Pacatianus the Great would soon be killed by his own men before his own arrival.

The genealogy of the blessed Cadoc arises from the most noble emperors of Rome, from the time of the incarnation of Jesus Christ, Augustus Cesar, in whose time Christ was born, begat Octavianus, Octavianus begat Tiberius, Tiberius begat Caius, Caius begat Claudius, Claudius begat Vespasian, Vespasian begat Titus, Titus begat Domitian, Domitian begat Nero, under whom the apostles Peter and Paul suffered, Nero begat Trajan, Trajan begat Adrian, Adrian begat Antonius, Antonius begat Commodus, Commodus begat Meobus, Meobus begat Severus, Severus begat Antonius, Antonius begat Aucanus, Aucanus begat Aurelian, Aurelian begat Alexander, Alexander begat Maximus, Maximus begat Gordian, Gordian begat Philip, Philip begat Decius, Decius begat Gallus, Callus begat Valerian, Valerian begat Cleopatra, Cleopatra begat Aurelian, Aurelian begat Titus, Titus begat Probus, Probus begat Carosius,

One literary tradition claims that Decius was betrayed by his successor Trebonianus Gallus, who was involved in a secret alliance with the Goths but this cannot be substantiated and was most likely a later invention since Gallus felt compelled to adopt Decius ' younger son, Gaius Valens Hostilianus, as joint emperor even though the latter was too young to rule in his own right.

Another strong point against Gallus ' treason is the fact that he adopted Hostilian, the younger son of Decius, after returning to Rome.

* Brutus, Cassius, Casca, Trebonius, Ligarius, Decius Brutus, Metellus Cimber, Cinna: Conspirators against Julius Caesar

* In renewed fighting, Pyrrhus of Epirus, leading the combined Tarantine, Oscan, Samnite, and Greek forces, wins a ' Pyrrhic victory ' against the Romans led by consul Publius Decius Mus at the Battle of Asculum, called such because his victory comes at a great cost to his own forces.

During his brief reign, Decius engaged in important operations against the Goths, who crossed the Danube to raid districts of Moesia and Thrace.

Decius was the first Roman Emperor to die in battle against a foreign enemy.

Historians have noted the many similarities between the story of Publius Decius Mus, and an event said to have taken place on Sicily in 258 when the Romans were fighting the First Punic War against Carthage.

Based on these news both consuls could march against the Samnites, Fabius advancing by way of Sora and Decius through the territory of the Sidicini.

After this, Edessa was again brought under Roman control by Decius and it was made a center of Roman operations against the Persian Sassanids.

The newly elected consuls for 297 BC, Quintus Fabius Maximus and Decius Mus led both armies against Samnium, Barbatus going as lieutenant general ( legatus ) under Maximus.

Saint Apollonia was one of a group of virgin martyrs who suffered in Alexandria during a local uprising against the Christians prior to the persecution of Decius.

The decree is brought to Decius ( on campaign against the Goths ) and he summons Valerian to bestow the honour.

Apparently, Licinianus, who was a senator, had the support of the Roman Senate and parts of the population when he initiated an uprising against Decius, who was fighting the Goths.

* I: The King's Gambit ( 70 BC ) — Decius uncovers a plot to subvert Lucullus ' army in the war against Mithridates.

Dionysius also describes the period where the city of Alexandria was subject to the legal persecution instituted by Emperor Decius against Christians.

It is possible that this Valens was Iulius Valens Licinianus, who usurped the purple in Rome during the absence of the Emperor Decius in the war against the Goths ( 250 ), and who was quickly executed.

Born in 95 BC into the prominent Caecilii Metelli family, a ( fictional ) nephew of Metellus Pius, Decius began his career serving as a military legate and scout commander, in the civil war against Quintus Sertorius, during which he received a scar from an Iberian spear.

* SPQR I: The King's Gambit: Decius uncovers a plot to subvert Lucullus's command in the East, on the eve of his campaign against Mithridates VI of Pontus.

After Decius Mus charged into enemy lines and was slain, consul Manlius Torquatus led his veteran reserve against Latin lines and killed or captured nearly three fourths of the Latin army.

But nothing shows more plainly the confidence felt in him than his being chosen by the emperor to settle the dispute between Aëtius and Caecina Decius Aginatius Albinus, the two highest officials in Gaul.

Under Decius he was nominated governor of the Rhine provinces of Noricum and Raetia and retained the confidence of his predecessor, Trebonianus Gallus, who asked him for reinforcements to quell the rebellion of Aemilianus in 253.

The Senate then recognized Decius as Emperor, giving him the attribute Traianus as a reference to the good emperor Trajan.

He was suffect consul and in 250 was nominated governor of the Roman province of Moesia Superior, an appointment that showed the confidence of Emperor Trajan Decius in him.

At the beginning of 251, Decius elevated Herennius to the title of Augustus making him his co-emperor.

P. Decius might have performed some heroic act which then enabled him to become the first of his family to reach the consulship in 340, but if so no detail of the historical event survives.

All that is known about him may be summed up thus: Under the Emperors Decius and Gratius ( AD 250-251 ), Pope Fabian sent out seven bishops from Rome to Gaul to preach the Gospel: Gatien to Tours, Trophimus to Arles, Paul to Narbonne, Saturnin to Toulouse, Denis to Paris, Austromoine to Clermont, and Martial to Limoges.

The Greeks of Rhegium who wanted to join him were massacred by Roman soldiers under the command of Decius Vibelius, who was proclaimed as ruler of the town.

At the time of the co-Emperors Decius and Gratus ( 250 / 51 AD ), according to Gregory of Tours, who calls him Stremonius, Pope Fabian sent out seven bishops from Rome to Gaul to preach the Gospel: Gatien to Tours, Trophimus to Arles, Paul to Narbonne, Saturninus to Toulouse, Denis to Paris, Martial to Limoges, and Austromoine to Clermont ( Historia Francorum, i. 30 ).

Gallus adopted Decius ' son Hostilian and made him co-ruler.

* X: A Point of Law ( 51-50 BC ) — While running for election to the office of praetor, Decius must deal with accusations that he murdered a man who had threatened to denounce him for actions he took while on Cyprus the previous year.

Although he then adds, " that some assert ", that this may have happened under Decius and Valerian at Chalcis, this statement ( ut alii affirmant ), adduced even by him as uncertain, is unlikely.

Augustus leaves Decius alone, knowing him to be powerless, and even occasionally calls on him to solve a mystery ( the subject matter of some of the short stories ).

After Decius solves the murder of Julia the Elder's lover in 22 BC, clearing Julia of all suspicion, Augustus offers him the position of Rex Sacrorum.

* SPQR X: A Point Of Law: While campaigning for the praetorship in Rome, Decius is accused of murder of a young aspiring politician who accused him of corruption.

John Gielgud had played Mark Antony at the Old Vic Theatre in 1930 and Cassius at the Shakespeare Memorial Theatre in Stratford-upon-Avon in 1950, James Mason had played Brutus at the Abbey Theatre in Dublin in the 1940s, and John Hoyt, who plays Decius Brutus, also played him in the 1937 stage version.