Constitution of the Roman Republic in the context of "Constitution of the Roman Kingdom"

Marcus Antonius (14 January 83 BC – 1 August 30 BC), commonly known in English as Mark Antony, was a Roman politician and general who played a critical role in the transformation of the Roman Republic from a constitutional republic into the autocratic Roman Empire.

Antony was a relative and supporter of Julius Caesar, and he served as one of his generals during the conquest of Gaul and Caesar's civil war. Antony was appointed administrator of Italy while Caesar eliminated political opponents in Greece, North Africa, and Spain. After Caesar's assassination in 44 BC, Antony joined forces with Lepidus, another of Caesar's generals, and Octavian, Caesar's great-nephew and adopted son, forming a three-man dictatorship known to historians as the Second Triumvirate. The Triumvirs defeated Caesar's killers, the Liberatores, at the Battle of Philippi in 42 BC, and divided the government of the Republic among themselves. Antony was assigned Rome's eastern provinces, including the client kingdom of Egypt, then ruled by Cleopatra VII, and was given the command in Rome's war against Parthia.

The constitutional reforms of Augustus were a series of laws that were enacted by the Roman Emperor Augustus between 30 BC and 2 BC, which transformed the Constitution of the Roman Republic into the Constitution of the Roman Empire. The era during which these changes were made began when Augustus defeated Mark Antony and Cleopatra at the Battle of Actium in 31 BC, and ended when the Roman Senate granted Augustus the title "Pater Patriae" in 2 BC.

Mixed government (or a mixed constitution) is a form of government that combines elements of democracy, aristocracy and monarchy, ostensibly making impossible their respective degenerations which are conceived in Aristotle's Politics as anarchy, oligarchy and tyranny. The idea was popularized during classical antiquity in order to describe the stability, the innovation and the success of the republic as a form of government developed under the Roman constitution.

Unlike classical democracy, aristocracy or monarchy, under a mixed government rulers are elected by citizens rather than acquiring their positions by inheritance or sortition (at the Greco-Roman time, sortition was conventionally regarded as the principal characteristic of classical democracy).

The Roman constitution was one of the general means by which the Roman people were governed. They were all unwritten. The first constitutional system of which anything meaningful is known is that of the Roman Republic. It developed after the overthrow of the Roman monarchy (traditionally dated to 509 BC). The second was that of the Roman Empire, which developed from that of the republic gradually during the early imperial period (from 27 BC on).

The Senate was the governing and advisory assembly of the aristocracy in the ancient Roman Republic. It was not an elected body, but one whose members were appointed by the consuls, and later by the censors, which were appointed by the aristocratic Centuriate Assembly. After a Roman magistrate served his term in office, it usually was followed with automatic appointment to the Senate. According to the Greek historian Polybius, the principal source on the Constitution of the Roman Republic, the Roman Senate was the predominant branch of government. Polybius noted that it was the consuls (the highest-ranking of the regular magistrates) who led the armies and the civil government in Rome, and it was the Roman assemblies which had the ultimate authority over elections, legislation, and criminal trials. However, since the Senate controlled money, administration, and the details of foreign policy, it had the most control over day-to-day life. The power and authority of the Senate derived from precedent, the high caliber and prestige of the senators, and the Senate's unbroken lineage, which dated back to the founding of the Republic in 509 BC. It developed from the Senate of the Roman Kingdom, and became the Senate of the Roman Empire.

Originally the chief magistrates, the consuls, appointed all new senators. They also had the power to remove individuals from the Senate. Around the year 318 BC, the "Ovinian Plebiscite" (plebiscitum Ovinium) gave this power to another Roman magistrate, the censor, who retained this power until the end of the Roman Republic. This law also required the censors to appoint any newly elected magistrate to the Senate. Thus, after this point in time, election to magisterial office resulted in automatic Senate membership. The appointment was for life, although the censor could impeach any senator.

The constitutional reforms of Sulla were a series of laws enacted by the Roman dictator Lucius Cornelius Sulla between 82 and 80 BC, reforming the constitution of the Roman Republic in a revolutionary way.

In the decades before Sulla had become dictator, Roman politics became increasingly violent. Shortly before Sulla's first consulship, the Romans fought the bloody Social War against their Italian allies, victorious mostly due to their immediate concession on the Italians' war goal of gaining Roman citizenship. Sulla's dictatorship followed more domestic unrest after the war and was a culmination in this trend for violence, with his leading an army on Rome for the second time in a decade and purging his opponents from the body politic in bloody proscriptions.

Optimates (/ˌɒptɪˈmeɪtiːz/, /ˈɒptɪmeɪts/; Latin for "best ones"; sg. optimas) and populares (/ˌpɒpjʊˈlɛəriːz, -jə-, -ˈleɪriːz/; Latin for "supporters of the people"; sg. popularis) are labels applied to politicians, political groups, traditions, strategies, or ideologies in the late Roman Republic. There is "heated academic discussion" as to whether Romans would have recognised an ideological content or political split in the label.

Among other things, optimates have been seen as supporters of the continued authority of the senate, politicians who operated mostly in the senate, or opponents of the populares. The populares have also been seen as focusing on operating before the popular assemblies, generally in opposition to the senate, using "the populace, rather than the senate, as a means [for advantage]". References to optimates (also called boni, "good men") and populares are found among the writings of Roman authors of the 1st century BC. The distinction between the terms is most clearly established in Cicero's Pro Sestio, a speech given and published in 56 BC, where he framed the two labels against each other.

The writings of Marcus Tullius Cicero constitute one of the most renowned collections of historical and philosophical work in all of classical antiquity. Cicero was a Roman politician, lawyer, orator, political theorist, philosopher, and constitutionalist who lived during the years of 106–43 BC. He held the positions of Roman senator and Roman consul (chief-magistrate) and played a critical role in the transformation of the Roman Republic into the Roman Empire. He was extant during the rule of prominent Roman politicians, such as those of Julius Caesar, Pompey, and Marc Antony. Cicero is widely considered one of Rome's greatest orators and prose stylists.

Cicero is generally held to be one of the most versatile minds of ancient Rome. He introduced the Romans to the chief schools of Greek philosophy, and also created a Latin philosophical vocabulary; distinguishing himself as a linguist, translator, and philosopher. A distinguished orator and successful lawyer, Cicero likely valued his political career as his most important achievement. Today he is appreciated primarily for his humanism and philosophical and political writings. His voluminous correspondence, much of it addressed to his friend Atticus, has been especially influential, introducing the art of refined letter writing to European culture. Cornelius Nepos, the 1st-century BC biographer of Atticus, remarked that Cicero's letters to Atticus contained such a wealth of detail "concerning the inclinations of leading men, the faults of the generals, and the revolutions in the government" that their reader had little need for a history of the period.