But Judaea was suffering a civil war between the two brothers Hyrcanus and Aristobulus. Pompey was hence asked to help quell their quarrels and help decide the matter of rule over Judaea (63 BC).
Pompey advised in favour of Hyrcanus. Aristobulus gave way to his brother. But his followers refused to accept and locked themselves up in the city of Jerusalem. Pompey hence besieged the city, conquered it after three months and left it to Hyrcanus. But his troops having effectively put Hyrcanus in power, Pompey left Judaea no longer an ally but a protectorate, which paid a tribute to Rome.