Livy, Periochae 76-80
Titus Livius or Livy (59 BCE - 17 CE): Roman historian, author of the authorized version of the history of the Roman republic.
A large part of Livy's History of Rome since the Foundation is now lost, but fortunately we have an excerpt, called the Periochae, which helps us reconstruct the general scope. This translation was made by Jona Lendering.
From Book 76
[76.1] [89 BCE] Deputy Aulus Gabinius had successfully waged war against the Lucanians and had captured many towns, when he was killed during the siege of a camp.
[76.2] Commander Sulpicius slaughtered all Marrucinians and accepted the surrender of the entire region.
[76.3] Proconsul Gnaeus Pompeius accepted the surrender of the Vestinians and Paelignians.
[76.4] The Marsians, broken in several battles by the deputies Lucius Cinna and Caecilius Pius, started to beg for peace.
[76.5] Gnaeus Pompeius captured Asculum.
[76.6] After the Italians had been defeated again by deputy Aemilius Mamercus, the leader of the Marsians and ringleader of the affair, Poppaedius Silo, fell in battle.
[76.7]  Ariobarzanes of Cappadocia and Nicomedes of Bithynia were dethroned by Mithridates, king of Pontus.
[76.8] Itnote[Book 76.] also contains an account of raids and plundering by the Thracians in Macedonia.
From Book 77
[77.1] When tribune of the plebs Publius Sulpicius, on the instigation of Carius Marius, had proposed dangerous laws (that the exiles would be recalled, new citizens and freedmen would be divided in voting districts, and Marius would be appointed leader against Mithridates, king of Pontus), and had used violence against the opposing consuls Quintus Pompeius and Lucius Sulla, killing Quintus Pompeius (the son of consul Quintus Pompeius and son-in-law of Sulla), Lucius Sulla entered the city with an army, fought a battle against the factions of Sulpicius and Marius in the city itself, and expelled them.
[77.2] Twelve members of this faction - among others father and son Marius - were proclaimed enemies by the Senate.
[77.3] When Publius Sulpicius was hiding in a villa, he was hunted down and killed on information given by his own slave.
[77.4] Because he had shown the way, the slave received the promised freedom, but was thrown from the Rocknote[The Tarpeian Rock.] because of his criminal betrayal of his master.
[77.5] The younger Gaius Marius crossed to Africa.
[77.6] The elder Gaius Marius hid himself in the marches near Minturnae, but was dragged out by the citizens. When a slave from Gaul was sent out to kill him, he withdrew because he feared the greatness of this man, and Marius was put on one of the town's ships and sent to Africa.
[77.7] Lucius Sulla reordered the state and sent out colonies.
[77.8] Consul Quintus Pompeius set out to take over the army of proconsul Gnaeus Pompeius, but was killed by the latter.
[77.9] King Mithridates of Pontus, having occupied Bithynia and Cappadocia and having expelled governor Aquilius, invaded Phrygia, a province of the Roman people, with an enormous army.
From Book 78
[78.1] Mithridates occupied Asia, cast into chains proconsul Quintus Oppius, did the same to his deputy Aquilius, and on Mithridates' command all Roman citizens in Asia were killed in one single day.
[78.2] He attacked the city of Rhodes, which alone had remained faithful to the Roman people, but was defeated in several naval battles, and retired.
[78.3] Archelaus, the deputy of the king, went to Greece with an army and occupied Athens.
[78.4] Itnote[Book 78.] also contains an account of the disorders in the cities and on the islands, as some wanted to side with Mithridates, and others with the Roman people.
From Book 79
[79.1]  When consul Lucius Cornelius Cinna was carrying dangerous laws by violence and arms, he along with six tribunes of the plebs was expelled from the city by his colleague Gnaeus Octavius and deprived of his office, but with bribes, he brought the army of Appius Claudius in his power and carried the war into the city, recalling Gaius Marius and other exiles from Africa.
[79.2] (In this war, two brothers, one from the army of Pompeius and one from Cinna's, unknowingly engaged, and when the winner was stripping the man he had killed, he cried heavily when he recognized his brother and built a pyre, on which he stabbed himself, and was consumed by the same fire.)
[79.3] And although [the civil war] could have been suppressed at the very beginning, by the treason of Gnaeus Pompeius (who supported both sides and did not bring help to the optimates till their position had become desparate) and by the slowness of the consul, the position of Cinna and Marius was strengthened, so that they were able to besiege the city with four armies, two of which were given to Quintus Sertorius and Carbo.
[79.4] Marius captured the colony at Ostia and sacked it cruelly.
From Book 80
[80.1] Citizenship was given to the Italian nations by the Senate.
[80.2] The Samnites, the only ones to take up arms again, sided with Cinna and Marius.
[80.3] They defeated deputy Plautius and his army.
[80.4] Cinna and Marius, together with Carbo and Sertorius, attacked the Janiculum, but were routed by consul Octavius and retreated.
[80.5] Marius captured the colonies at Antium and Aricia and Lanuvium.
[80.6] When, because of the slowness and perfidy of both their leaders and their soldiers (who were bribed and did not want to fight or moved to other regions), the optimates had lost all hope of holding out, Cinna and Marius were received in the city, which they treated with murder and rape as if it were conquered. Consul Gnaeus Octavius was killed and all noble members of the opposite party butchered, like Marcus Antonius (a man of great eloquence), and Gaius and Lucius Caesar, whose heads were placed on the speaker's platform
[80.7] The younger Crassus was killed by the knights of Fimbria, and the elder Crassus, wishing to avoid a fate unworthy of his dignity, stabbed himself with his sword.
[80.8] And without even the appearance of election, they [Cinna and Marius] appointed themselves consuls for the next year.
[80.9]  On the very day of the beginning of his magistracy, Marius ordered that the senator Sextus Licinius was to be thrown from the rock.note[The Tarpeian Rock.] After many crimes, Marius died on the Ides of January. When we take everything into account, he had been a man about whom it was not easy to say whether he was more excellent in times of war than he was dangerous in times of peace.
[80.10] It can therefore be said that as much as he saved the state as a soldier, so much he damaged it as a citizen - first by his tricks, later by his revolutionary actions.