Gabiniani The Gabiniani ( in English Gabinians ) were 2 , 000 Roman legionaries and 500 Roman auxiliary cavalry left in Egypt by the general Aulus Gabinius after his military restoration of Ptolemy XII on the Egyptian throne in 55 BC . The soldiers were left to protect the king , but they soon adopted the manners of their new country and became completely alienated from the Roman Republic . After the death of Ptolemy XII in 51 BC they helped his son Ptolemy XIII in the power struggle against his sister Cleopatra VII and even involved Julius Caesar , the powerful supporter of Cleopatra , in the Alexandrinian war ( 48 - 47 BC ) in violent battles . Protecting power of Ptolemy XII in Egypt . In 58 BC Ptolemy XII had to leave Egypt and went into exile in Rome . Three years later Aulus Gabinius , the Roman proconsul of Syria , restored the king after a short campaign to the throne . Then he left a part of his army , the " Gabiniani " , in Egypt for the protection of the future reign of the king . These Roman troops also included Gallic and German horsemen . Because Egypt was nominally independent , the " Gabiniani " were not a Roman occupying army but mercenaries of Ptolemy XII . According to the report of Julius Caesar , they soon adopted the dissipated way of life of the Alexandrians , while they neglected Roman discipline . Nevertheless they still possessed a great fighting strength because Caesar described them as very dangerous enemies in the Alexandrinian war . They married Egyptian women and had already fathered children with them before the arrival of Caesar in Egypt ( 48 BC ) . So they lost more and more the ties to Rome and became a loyal protecting power of Ptolemy XII , who used them in fights against rebellious subjects . Conflict with Cleopatra VII . After the death of Ptolemy XII ( 51 BC ) his two oldest surviving children , Ptolemy XIII and Cleopatra VII , were supposed to jointly succeed him on the throne as husbands , but the young queen soon ousted her brother and husband from the power and ruled alone . She quickly came into a serious conflict with the " Gabiniani " . In 53 BC the powerful Parthians had inflicted a devastating defeat on the Romans in the Battle of Carrhae , and three years later – at the beginning of the year 50 BC – the governor of Syria , Marcus Calpurnius Bibulus , sent two of his sons to Egypt to recruit the " Gabiniani " for the war against the Parthians . The " Gabiniani " , however , did not want to give up their comfortable life in the Ptolemaic Empire to fight against the dangerous Parthians , and killed the sons of Bibulus . Cleopatra continued the pro - Roman policies of her father and did not hesitate to have the murderers arrested and handed over in chains to Bibulus , because a simple averment of the queen not to be guilty of the crime would surely not have been enough for the mourning father . This action turned the " Gabiniani " into bitter enemies of the queen , but it was more important for Cleopatra to maintain good relations with Rome . Valerius Maximus claims that the Syrian proconsul sent the murderers back because not he but the senate in Rome was responsible for the punishment of the criminals , who were still Roman citizens . The German historian Christoph Schäfer does not believe this version and assumes instead that the proconsul himself did pronounce the judgement , since on the one hand he had the legal authority and on the other , he should have sent the murderers to Rome and not to Egypt if he really thought that only the senate had the necessary competence . Christoph Schäfer believes that Cleopatra ’ s break with the " Gabiniani " was the main cause of her loss of power that soon ensued . At this time at the latest the " Gabiniani " joined the party of Ptolemy XIII and his three influential guardians and advisors , Pothinus , Achillas , and Theodotus of Chios . In the spring of 49 BC Gnaeus Pompeius , the oldest son of the triumvir Pompey , came to Egypt to ask for military aid in the civil war against Julius Caesar that had just broken out . At this time Ptolemy XIII had succeeded in sharing the power with his older sister Cleopatra and both rulers complied with the petition . Among other things they sent 500 horsemen of the " Gabiniani " to Pompey . This time the " Gabiniani " did not refuse to go to war . At the end of 49 BC Cleopatra was driven out of Alexandria at the instigation of Pothinus . Probably in connection with this action , Caesar accuses the " Gabiniani " that they were so much used to the old customs of the Alexandrinian soldiers that they demanded the execution of friends of kings , tried to raise their pay by besieging the palace and that they deposed kings and brought other men to power . After his decisive defeat in the Battle of Pharsalus , Pompey fled to the coast of Egypt and demanded help and support from the Ptolemaic government . The advisors of Ptolemy XIII were not willing to get involved into the Roman civil war and decided the murder of Pompey in an attempt to please the victorious Caesar . Pothinus and his companions allegedly also feared that Pompey would try to incite the former Roman soldiers in the Ptolemaic army – who partly had earlier fought under his command – to gain control over Egypt . It is very doubtful , however , whether the " Gabiniani " could have been convinced to take part in such a step because they were already so deeply rooted in Egypt . Indeed two leading members of the " Gabiniani " , the former tribune Lucius Septimius and the centurion Salvius , participated in the assassination of Pompey ( 25 July 48 BC according to the Julian calendar ) . War against Caesar . Caesar arrived in Egypt a few days after the assassination of Pompey . In spite of the elimination of his enemy , he did not leave the country and supported the expelled Cleopatra in the Ptolemaic power struggle . Pothinus organized military opposition against Caesar . In the Alexandrinian war that followed , the " Gabiniani " played an important role : they were the core divisions of Achillas ' army that comprised 20 . 000 infantrymen and 2000 cavalrymen . The forces of Caesar were one - fifth the size of his opponent ' s . Caesar relates in his " Commentarii de Bello Civili " that fugitive criminals and exiles from the neighbouring Roman provinces had joined the Gabiniani because the government recruited them to swell the ranks of their army . After the successful conclusion of the Alexandrinian war , Caesar replaced the " Gabiniani " by three reliable legions , the XXVII , XXVIII and XXIX , that served as the Roman occupying army of Egypt . These troops were to protect the reign of Cleopatra but also to ensure the queen ' s loyalty to Rome .