Question: The forces of Mark Antony and Octavian fought the killers of the man behind the Julian calendar where?

full_context: Document 1: Roman Republic: By 59 BC an unofficial political alliance known as the First Triumvirate was formed between Gaius Julius Caesar, Marcus Licinius Crassus, and Gnaeus Pompeius Magnus ("Pompey the Great") to share power and influence. In 53 BC, Crassus launched a Roman invasion of the Parthian Empire (modern Iraq and Iran). After initial successes, he marched his army deep into the desert; but here his army was cut off deep in enemy territory, surrounded and slaughtered at the Battle of Carrhae in which Crassus himself perished. The death of Crassus removed some of the balance in the Triumvirate and, consequently, Caesar and Pompey began to move apart. While Caesar was fighting in Gaul, Pompey proceeded with a legislative agenda for Rome that revealed that he was at best ambivalent towards Caesar and perhaps now covertly allied with Caesar's political enemies. In 51 BC, some Roman senators demanded that Caesar not be permitted to stand for consul unless he turned over control of his armies to the state, which would have left Caesar defenceless before his enemies. Caesar chose civil war over laying down his command and facing trial.
Document 2: Gregorian calendar: The Gregorian reform contained two parts: a reform of the Julian calendar as used prior to Pope Gregory XIII's time and a reform of the lunar cycle used by the Church, with the Julian calendar, to calculate the date of Easter. The reform was a modification of a proposal made by Aloysius Lilius. His proposal included reducing the number of leap years in four centuries from 100 to 97, by making 3 out of 4 centurial years common instead of leap years. Lilius also produced an original and practical scheme for adjusting the epacts of the moon when calculating the annual date of Easter, solving a long-standing obstacle to calendar reform.
Document 3: 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 conflict between the so - called Optimates and the so - called Populares.
Document 4: Gregorian calendar: The Gregorian calendar was a reform of the Julian calendar instituted in 1582 by Pope Gregory XIII, after whom the calendar was named, by papal bull Inter gravissimas dated 24 February 1582. The motivation for the adjustment was to bring the date for the celebration of Easter to the time of year in which it was celebrated when it was introduced by the early Church. Although a recommendation of the First Council of Nicaea in 325 specified that all Christians should celebrate Easter on the same day, it took almost five centuries before virtually all Christians achieved that objective by adopting the rules of the Church of Alexandria (see Easter for the issues which arose).
Document 5: Julian calendar: The Julian calendar, proposed by Julius Caesar in 708 AUC (46 BC/BCE), was a reform of the Roman calendar. It took effect on 1 January 709 AUC (45 BC/BCE), by edict. It was the predominant calendar in the Roman world, most of Europe, and in European settlements in the Americas and elsewhere, until it was gradually replaced by the Gregorian calendar, promulgated in 1582 by Pope Gregory XIII.
Document 6: Roman Republic: However, civil war flared again when the Second Triumvirate of Octavian, Lepidus and Mark Antony failed. The ambitious Octavian built a power base of patronage and then launched a campaign against Mark Antony. At the naval Battle of Actium off the coast of Greece, Octavian decisively defeated Antony and Cleopatra. Octavian was granted a series of special powers including sole "imperium" within the city of Rome, permanent consular powers and credit for every Roman military victory, since all future generals were assumed to be acting under his command. In 27 BC Octavian was granted the use of the names "Augustus" and "Princeps", indicating his primary status above all other Romans, and he adopted the title "Imperator Caesar" making him the first Roman Emperor.
Document 7: Roman Republic: Caesar was now the primary figure of the Roman state, enforcing and entrenching his powers. His enemies feared that he had ambitions to become an autocratic ruler. Arguing that the Roman Republic was in danger, a group of senators hatched a conspiracy and assassinated Caesar at a meeting of the Senate in March 44 BC.  Mark Antony, Caesar's lieutenant, condemned Caesar's assassination, and war broke out between the two factions. Antony was denounced as a public enemy, and Caesar's adopted son and chosen heir, Gaius Octavianus, was entrusted with the command of the war against him. At the Battle of Mutina Mark Antony was defeated by the consuls Hirtius and Pansa, who were both killed.
Document 8: Gregorian calendar: The Gregorian calendar is internationally the most widely used civil calendar. It is named after Pope Gregory XIII, who introduced it in October 1582.
Document 9: Julian calendar: The Julian calendar has a regular year of 365 days divided into 12 months, as listed in the table below. A leap day is added to February every four years. The Julian year is, therefore, on average 365.25 days long. It was intended to approximate the tropical (solar) year. Although Greek astronomers had known, at least since Hipparchus, a century before the Julian reform, that the tropical year was slightly shorter than 365.25 days, the calendar did not compensate for this difference. As a result, the calendar year gains about three days every four centuries compared to observed equinox times and the seasons. This discrepancy was corrected by the Gregorian reform of 1582. The Gregorian calendar has the same months and month lengths as the Julian calendar, but, in the Gregorian calendar, years evenly divisible by 100 are not leap years, except that years evenly divisible by 400 remain leap years. Consequently -- since 16 February Julian / 1 March 1900 Gregorian and until 15 February Julian / 28 February 2100 Gregorian -- the Julian calendar is currently 13 days behind the Gregorian calendar.
Document 10: Battle of Pharsalus: The Battle of Pharsalus was the decisive battle of Caesar's Civil War. On 9 August 48 BC at Pharsalus in central Greece, Gaius Julius Caesar and his allies formed up opposite the army of the republic under the command of Gnaeus Pompeius Magnus ("Pompey the Great"). Pompey had the backing of a majority of the senators, of whom many were optimates, and his army significantly outnumbered the veteran Caesarian legions.
Document 11: Assassination of Julius Caesar: Two days after the assassination, Mark Antony summoned the senate and managed to work out a compromise in which the assassins would not be punished for their acts, but all of Caesar's appointments would remain valid. By doing this, Antony most likely hoped to avoid large cracks in government forming as a result of Caesar's death. Simultaneously, Antony diminished the goals of the conspirators. The result unforeseen by the assassins was that Caesar's death precipitated the end of the Roman Republic. The Roman lower classes, with whom Caesar was popular, became enraged that a small group of aristocrats had sacrificed Caesar. Antony, who had been drifting apart from Caesar, capitalised on the grief of the Roman mob and threatened to unleash them on the Optimates, perhaps with the intent of taking control of Rome himself. But, to his surprise and chagrin, Caesar had named his grandnephew Gaius Octavius his sole heir, bequeathing him the immensely potent Caesar name as well as making him one of the wealthiest citizens in the Republic. Upon hearing of his adopted father's death, Octavius abandoned his studies in Apollonia and sailed across the Adriatic Sea to Brundisium. Octavius became Gaius Julius Caesar Octavianus or Octavian, the son of the great Caesar, and consequently also inherited the loyalty of much of the Roman populace. Octavian, aged only 18 at the time of Caesar's death, proved to have considerable political skills, and while Antony dealt with Decimus Brutus in the first round of the new civil wars, Octavian consolidated his tenuous position. Antony did not initially consider Octavius a true political threat due to his young age and inexperience, but Octavius quickly gained the support and admiration of Caesar's friends and supporters.
Document 12: Julian calendar: The Julian calendar, proposed by Julius Caesar in 46 BC (708 AUC), was a reform of the Roman calendar. It took effect on 1 January 45 BC (AUC 709), by edict. It was the predominant calendar in the Roman world, most of Europe, and in European settlements in the Americas and elsewhere, until it was refined and gradually replaced by the Gregorian calendar, promulgated in 1582 by Pope Gregory XIII. The Julian calendar gains against the mean tropical year at the rate of one day in 128 years. For the Gregorian the figure is one day in 3,030 years. The difference in the average length of the year between Julian (365.25 days) and Gregorian (365.2425 days) is 0.002%.
Document 13: Roman Republic: After the assassination, Mark Antony formed an alliance with Caesar's adopted son and great-nephew, Gaius Octavian. Along with Marcus Lepidus, they formed an alliance known as the Second Triumvirate. They held powers that were nearly identical to the powers that Caesar had held under his constitution. As such, the Senate and assemblies remained powerless, even after Caesar had been assassinated. The conspirators were then defeated at the Battle of Philippi in 42 BC. Eventually, however, Antony and Octavian fought against each other in one last battle. Antony was defeated in the naval Battle of Actium in 31 BC, and he committed suicide with his lover, Cleopatra. In 29 BC, Octavian returned to Rome as the unchallenged master of the Empire and later accepted the title of Augustus ("Exalted One"). He was convinced that only a single strong ruler could restore order in Rome.
Document 14: Roman Republic: Clodius formed armed gangs that terrorised the city and eventually began to attack Pompey's followers, who in response funded counter-gangs formed by Titus Annius Milo. The political alliance of the triumvirate was crumbling. Domitius Ahenobarbus ran for the consulship in 55 BC promising to take Caesar's command from him. Eventually, the triumvirate was renewed at Lucca. Pompey and Crassus were promised the consulship in 55 BC, and Caesar's term as governor was extended for five years. Crassus led an ill-fated expedition with legions led by his son, Caesar's lieutenant, against the Kingdom of Parthia. This resulted in his defeat and death at the Battle of Carrhae. Finally, Pompey's wife, Julia, who was Caesar's daughter, died in childbirth. This event severed the last remaining bond between Pompey and Caesar.
Document 15: History of calendars: The Gregorian calendar was introduced as a refinement of the Julian calendar in 1582, and is today in worldwide use as the de facto calendar for secular purposes.
ground_truth: Philippi in Macedonia
sub_queries: The Julian calendar was named for whom? Answer: Julius Caesar
where did the battle take place in Julius Caesar Answer: Philippi in Macedonia