The Principate: emperor, Senate, army

Detail

What the Principate was

• Augustus founded the Principate in 27 BCE. He was the first emperor. He alone held real power. He alone was the true source of authority.
• But a polite fiction was kept up. Augustus was called only Princeps — "leading citizen", not king, not master.
• Rome had thrown out its kings long ago. The word "king" was hated.

• So the new one-man rule was dressed up in old Republican clothes.

• The fiction was kept out of respect for the Senate. The Senate had run Rome through the Republic (509–27 BCE).

• The title princeps was not new. In the Republic it belonged to the leading member of the Senate — the princeps senatus. Augustus borrowed an old, safe word, which helped him claim he was restoring the Republic after the civil wars of the 1st century BCE [2].
• In January 27 BCE Augustus publicly "handed the State back to the free disposal of the Senate and people". In the same act he was given a 10-year charge of a block of provinces — Spain, Gaul and Syria — the three regions that held most of the army [3].

• So he gave away the show and kept the swords. That is the Principate in one line.

• The Principate mixed Republican forms with monarchy's real powers [3]. Princeps stayed the emperor's unofficial title from Augustus (r. 27 BCE–14 CE) down to Diocletian (r. 284–305 CE) [2].

The Senate — who they were

• The Senate represented the aristocracy: the wealthiest families, mainly landowning.
• They were of Roman descent first; later Italian families joined too.
• Membership was for life.
• Wealth and office counted more than birth. A rich man who held high office could get in. Pure blue blood by itself was not enough.
• The Senate still met, still functioned, still debated — but the emperor as princeps stayed in control of government [3].

Why our histories sound pro-Senate

• Most surviving histories were written from a senatorial viewpoint. Many writers were senators themselves or wrote for that class.
• So emperors were judged by how they behaved towards the Senate, not by how they ruled the provinces.
• The "worst" emperors in these books are the ones who were hostile, suspicious or violent towards senators.
• Exam point: this is a source-bias problem. A "bad" emperor in Tacitus or Suetonius may have been popular with soldiers or provincials. The record leans one way.

The army — a paid professional force

• Rome's army was a paid professional army. This was a distinctive Roman feature.
• Contrast with Iran (the Parthian/Sasanian side), which used a conscripted force — men called up, not career soldiers.
• Minimum service: 25 years. A long career, not a season's duty.
• Soldiers got more than wages: donatives (cash gifts), a share of booty, and retirement bonuses. These came from a special military treasury, the aerarium militare, set up in 6 CE, funded by a sales tax and death duties paid by Roman citizens [4].
• Augustus also created a permanent household force in 27 BCE — the Praetorian Guard, nine cohorts stationed around Rome. Septimius Severus reorganised it in 193 CE, recruiting from the legions [4].
• The legion was the largest permanent unit and the base of the whole military system [4].

Why the army mattered politically

• The army was the largest organised body in the empire — 600,000 men by the fourth century.
• It could decide an emperor's fate: make him, unmake him, kill him.
• Soldiers agitated for pay and better conditions, sometimes breaking into open mutiny.
• The Senate feared and hated the army — an unpredictable source of violence the senators could not control.

The three players and the rule of stability

• Emperor, aristocracy (Senate) and army were the three main players of Roman politics.
• Success depended on control of the army.
• One emperor + one loyal army = stable rule.

• Divided armies = civil war.

• Yet the first two centuries were largely stable. Only 69 CE — the "year of four emperors" — was a real crisis.

• The four were Galba (68–69), Otho (Jan–April 69), Vitellius (July–Dec 69), Vespasian (69–79) [5].
• Each stood for a different army bloc: Galba for the legions of Spain, Otho for the Praetorian Guard, Vitellius for the Army of the Rhine, Vespasian for a coalition of the Danube and Euphrates armies [5].
• Vespasian was first proclaimed by the two Egyptian legions, then by legions elsewhere [5].
• The year followed Nero's fall (68 CE) and the end of the Julio-Claudian dynasty. It laid bare the military basis of the Principate [5].

Succession

• Succession ran by family descent — either natural (a real son) or adoptive (a chosen heir made a legal son).
• Augustus adopted Tiberius (r. 14–37 CE) so power passed smoothly.
• Adoption was the safety valve when there was no son. It let the emperor pick a competent man and still keep the family form.

Expansion stops

• After Augustus, expansion largely ceased. Romans felt the inherited empire was big enough.
• The Augustan age is remembered for peace, not conquest.
• The one major campaign: Trajan's occupation of territory across the Euphrates, 113–17 CE.
• Trajan moved in 113/114 to put a pro-Roman king back on the Armenian throne after the Parthians removed him; in 115 he annexed upper Mesopotamia, then went down the Tigris and took the Parthian capital Ctesiphon; he reached the Persian Gulf [6].
• The Parthian princes, till then fighting each other, united against him. After a setback at the walls of Hatra, Trajan gave up and died on the way home [6].

• His successors abandoned the conquest. Hadrian (r. 117–138) was in the East in 117 and at once gave up Armenia, Mesopotamia and Assyria [6].

• Famous story: at the Persian Gulf, Trajan watched a merchant ship sailing for India and wished he were as young as Alexander.

The real method — swallowing client kingdoms

• What was characteristic was not war but absorption of 'dependent' client kingdoms into direct provincial territory.

• A client kingdom = a local king left on his throne, loyal to Rome, paying and obeying. Later Rome simply took it over and made it a province.

• Some were very rich. Herod's kingdom yielded 5.4 million denarii a year — worth over 125,000 kg of gold.

• The denarius was the Roman silver coin, about 4.5 g of pure silver.
• Point to remember: Rome grew richer by annexation and taxation, not only by battle.

Prelims Hooks

• Principate founded in 27 BCE by Augustus; the emperor's title was Princeps = "leading citizen".
• The Roman Republic ran 509–27 BCE; the Senate controlled Rome in that period.
• In January 27 BCE Augustus was given a 10-year command over Spain, Gaul and Syria — the provinces holding most of the army [3].
• Princeps stayed the unofficial imperial title from Augustus to Diocletian (r. 284–305 CE) [2].
• Rome had a paid professional army with a 25-year minimum service; Iran's army was conscripted.
• Army strength reached 600,000 by the fourth century CE.
• The military treasury aerarium militare was set up in 6 CE; the Praetorian Guard (9 cohorts) in 27 BCE [4].
• 69 CE = year of four emperors: Galba, Otho, Vitellius, Vespasian [5].
• Tiberius (r. 14–37 CE) succeeded Augustus by adoption.
• Trajan's trans-Euphrates campaign: 113–17 CE; reached Ctesiphon and the Persian Gulf; Hadrian gave it up in 117 CE [6].
• Herod's kingdom gave 5.4 million denarii a year; 1 denarius ≈ 4.5 g pure silver.

Mains Points

• The Principate was a monarchy wearing Republican clothes. Augustus kept the Senate, the old titles and the old offices, but held the provinces with the legions. Show how form and substance split: "restoring the Republic" in 27 BCE while taking a 10-year command over the army provinces [3]. Useful for any question on how empires legitimise new power using old institutions.
• Source bias shapes our picture of Roman rule. Surviving histories are senatorial. Emperors are graded on their manners towards senators, not on provincial administration, taxation or army welfare. Good example for a GS-I answer on the limits of elite-written sources.
• A paid professional army is both strength and danger. The 25-year service and the aerarium militare (6 CE) made a disciplined, permanent force [4] — but pay grievances caused mutinies and 69 CE showed that whoever controlled the legions controlled the throne [5]. Compare with Iran's conscript army: professionalism buys reach, and costs political control.
• Rome after Augustus grew by absorption, not conquest. Trajan's 113–17 CE campaign was the exception and was reversed by Hadrian in 117 [6]. The normal route was turning client kingdoms into provinces — cheap, and hugely profitable (Herod's 5.4 million denarii). Use for questions on how ancient empires financed themselves.