Question: Gaius Cassius Longinus, was a Roman senator, a leading instigator of the plot to kill Julius Caesar, and the brother in-law of Marcus Junius Brutus, he commanded troops with Brutus during the Battle of Philippi against the combined forces of which Roman politician and general who played a critical role in the transformation of the Roman Republic from an oligarchy into the autocratic Roman Empire?

full_context: Document 1: Mark Antony: Marcus Antonius (Latin: ; January 14, 83 BC – August 1, 30 BC), commonly known in English as Mark or Marc Antony, was a Roman politician and general who played a critical role in the transformation of the Roman Republic from an oligarchy into the autocratic Roman Empire.
Document 2: History of the Roman Empire: The history of the Roman Empire covers the history of Ancient Rome from the fall of the Roman Republic in 27 BC until the abdication of the last Western emperor in 476 AD. Rome had begun expanding shortly after the founding of the Republic in the 6th century BC, though it did not expand outside of the Italian Peninsula until the 3rd century BC. Civil war engulfed the Roman state in the mid 1st century BC, first between Julius Caesar and Pompey, and finally between Octavian and Mark Antony. Antony was defeated at the Battle of Actium in 31 BC. In 27 BC the Senate and People of Rome made Octavian "imperator" ("commander") thus beginning the Principate, the first epoch of Roman imperial history usually dated from 27 BC to 284 AD; they later awarded him the name Augustus, "the venerated". The success of Augustus in establishing principles of dynastic succession was limited by his outliving a number of talented potential heirs: the Julio-Claudian dynasty lasted for four more emperors—Tiberius, Caligula, Claudius, and Nero—before it yielded in 69 AD to the strife-torn Year of Four Emperors, from which Vespasian emerged as victor. Vespasian became the founder of the brief Flavian dynasty, to be followed by the Nerva–Antonine dynasty which produced the "Five Good Emperors": Nerva, Trajan, Hadrian, Antoninus Pius and the philosophically inclined Marcus Aurelius. In the view of the Greek historian Dio Cassius, a contemporary observer, the accession of the emperor Commodus in 180 AD marked the descent "from a kingdom of gold to one of rust and iron"—a famous comment which has led some historians, notably Edward Gibbon, to take Commodus' reign as the beginning of the decline of the Roman Empire.
Document 3: Roman Republic: The Roman Republic (Latin: Res publica Romana ; ] ) was the era of ancient Roman civilization beginning with the overthrow of the Roman Kingdom, traditionally dated to 509 BC, and ending in 27 BC with the establishment of the Roman Empire. It was during this period that Rome's control expanded from the city's immediate surroundings to hegemony over the entire Mediterranean world.
Document 4: Augustus: Augustus (Latin: "Imperātor Caesar Dīvī Fīlius Augustus" ; 23 September 63 BC – 19 August 14 AD) was the founder of the Roman Principate and considered the first Roman emperor, controlling the Roman Empire from 27 BC until his death in AD 14. He was born Gaius Octavius into an old and wealthy equestrian branch of the plebeian "gens" Octavia. His maternal great-uncle Julius Caesar was assassinated in 44 BC, and Octavius was named in Caesar's will as his adopted son and heir, then known as Octavianus (Anglicized as Octavian). He, Mark Antony, and Marcus Lepidus formed the Second Triumvirate to defeat the assassins of Caesar. Following their victory at the Battle of Philippi, the Triumvirate divided the Roman Republic among themselves and ruled as military dictators. The Triumvirate was eventually torn apart by the competing ambitions of its members. Lepidus was driven into exile and stripped of his position, and Antony committed suicide following his defeat at the Battle of Actium by Octavian in 31 BC.
Document 5: Assassination of Julius Caesar: The assassination of Julius Caesar was the result of a conspiracy by many Roman senators. Led by Gaius Cassius Longinus, Decimus Junius Brutus, and Marcus Junius Brutus, they stabbed Julius Caesar to death in a location adjacent to the Theatre of Pompey on the Ides of March (March 15), 44 BC. Caesar was the dictator of the Roman Republic at the time, having recently been declared "dictator perpetuo" by the Senate. This declaration made several senators fear that Caesar wanted to overthrow the Senate in favor of tyranny. The conspirators were unable to restore the Roman Republic. The ramifications of the assassination led to the Liberators' civil war and, ultimately, to the Principate period of the Roman Empire.
Document 6: Ptolemy XIV of Egypt: Ptolemy XIV (Greek: Πτολεμαῖος , "Ptolemaĩos", who lived 60 BC/59 BC–44 BC and reigned 47 BC–44 BC), was a son of Ptolemy XII of Egypt and one of the last members of the Ptolemaic dynasty of Egypt. Following the death of his older brother Ptolemy XIII of Egypt on January 13, 47 BC, he was proclaimed Pharaoh and co-ruler by their older sister and remaining Pharaoh, Cleopatra VII of Egypt. He and Cleopatra were married, but Cleopatra continued to act as lover of Roman dictator Julius Caesar. Ptolemy is considered to have reigned in name only, with Cleopatra keeping actual authority to herself. On March 15, 44 BC Caesar was murdered in Rome by a group of conspirators whose most notable members were Marcus Junius Brutus and Gaius Cassius Longinus. Ptolemy soon followed him in death. An inscription mentioning him as alive was dated at July 26, 44 BC. It has been assumed but remains uncertain that Cleopatra poisoned her co-ruler, with aconite, to replace him with his nephew Ptolemy XV Caesarion, her son by Caesar who was proclaimed co-ruler on September 2, 44 BC and whom his mother intended to support as successor of his father.
Document 7: Marcus Vipsanius Agrippa: Marcus Vipsanius Agrippa ( ; 64/62 BC – 12 BC) was a Roman consul, statesman, general and architect. He was a close friend, son-in-law, and lieutenant to Octavian and was responsible for the construction of some of the most notable buildings in the history of Rome and for important military victories, most notably at the Battle of Actium in 31 BC against the forces of Mark Antony and Cleopatra. As a result of these victories Octavian became the first Roman Emperor, adopting the name of Augustus. Agrippa assisted Augustus in making Rome a city of marble and renovating aqueducts to give all Romans, from every social class, access to the highest quality public services. He was responsible for the creation of many baths, porticoes and gardens, as well as the original Pantheon. Agrippa was also father-in-law to the second Emperor Tiberius, maternal grandfather to Caligula, and maternal great-grandfather to the Emperor Nero.
Document 8: Gaius Cassius Longinus: Gaius Cassius Longinus (] ; October 3, before 85 BC – October 3, 42 BC) was a Roman senator, a leading instigator of the plot to kill Julius Caesar, and the brother in-law of Marcus Junius Brutus. He commanded troops with Brutus during the Battle of Philippi against the combined forces of Mark Antony and Octavian, Caesar's former supporters, and committed suicide after being defeated by Mark Antony.
Document 9: Philippi (Rome): "Philippi" is the sixth episode of the second season of the television series "Rome". The episode portrays the civil war between the Second Triumvirate and the combined forces of Marcus Junius Brutus and Gaius Cassius Longinus, murderers of Julius Caesar. The Battle of Philippi is featured in this episode.
Document 10: Liberators' civil war: The Liberators' civil war was started by the Second Triumvirate to avenge Julius Caesar's murder. The war was fought by the forces of Mark Antony and Octavian (the Second Triumvirate members) against the forces of Caesar's assassins Marcus Junius Brutus and Gaius Cassius Longinus in 42 BC.
Document 11: Lucius Junius Brutus: Lucius Junius Brutus ( ) was the founder of the Roman Republic and traditionally one of the first consuls in 509 BC. He was claimed as an ancestor of the Roman gens Junia, including Decimus Junius Brutus and Marcus Junius Brutus, the most famous of Julius Caesar's assassins.
Document 12: Marcus Licinius Crassus: Marcus Licinius Crassus ( ; c. 115–53 BC) was a Roman general and politician who played a key role in the transformation of the Roman Republic into the Roman Empire. Amassing an enormous fortune during his life, Crassus is, excepting Augustus Caesar, considered the wealthiest man in Roman history.
Document 13: Marcus Horatius Pulvillus: Marcus Horatius Pulvillus was an aristocrat before and during the early Roman Republic at the time of the overthrow of the Roman monarchy. He was a suffect consul in 509 BC and elected again in 507 BC, according to the Varronian chronology.
Document 14: Augustus (Williams novel): Born Gaius Octavius Thurinus, the young future-emperor was adopted by his great-uncle, Julius Caesar, after demonstrating promising wit and skill. After his great-uncle's assassination, Augustus (at this time known as Gaius Julius Caesar Octavianus) took vengeance upon Caesar's murderers, and through tactical political moves, became one of Rome's three “Triumvirs" alongside Marc Antony and Marcus Aemilius Lepidus. After defeating the other two triumvirs, and obtaining sole power over the Roman State, Augustus (known as "Imperator" Caesar Divi Filius), began taking measures to secure and increase his power. As a result, Augustus gave orders to exterminate Cleopatra's teenaged son, allegedly commenting, "too many Caesars is no good thing." (As it was the common belief that her son was of Julius Caesar's bloodline.) In light of such orders, Cleopatra and Marc Antony—lovers at the time—committed suicide.
Document 15: Battle of Philippi: The Battle of Philippi was the final battle in the Wars of the Second Triumvirate between the forces of Mark Antony and Octavian (of the Second Triumvirate) and the leaders of Julius Caesar's assassination, Marcus Junius Brutus and Gaius Cassius Longinus in 42 BC, at Philippi in Macedonia. The Second Triumvirate declared this civil war ostensibly to avenge Julius Caesar's assassination in 44 BC, but the underlying cause was a long-brewing class conflict between the "ancien regime" represented in the Senate (Optimates), and the rising class (Populares).
ground_truth: Mark Antony