In 87 BC, Hybrida accompanied Lucius Cornelius Sulla on his campaign against Mithridates VI of Pontus either as a military tribune or as a legatus. Two years prior, the Mithridatic Wars had begun due to a dispute between Mithridates and Nicomedes III of Bithynia over the Roman province of Cappadocia. Mithridates invaded and conquered both Bithynia and Cappadocia before moving on to invade the Roman province of Asia, here he massacred all Roman citizens he could find, he then sent troops to invade Greece, which in turn spurred some of the city-states to rebel against Rome. At the time Rome was embroiled in internal conflict through the Social Wars from 91 to 88 and then almost immediately after, an uprising occurred in Rome which further delayed Sulla's response to Mithridates. After the rebellion in Rome was dealt with, Sulla, accompanied by Hybrida, marched on Greece to face the Mithridatic-Greek armies under the command of Archelaus and Aristion. The First Mithridatic War continued from 86 to 83. During this campaign, Sulla drove the Mithridatic-Greek armies back towards Athens and besieged them there. After capturing Athens, Sulla marched north and defeated two large Mithridatic armies at Chaeronea and Orchomenus. He invaded Asia Minor the following year and then successfully forced a peace with Mithridates in 83. Sulla returned to Italia in 83, leaving Lucullus to command forces in Asia and Hybrida to command a small cavalry force in Achaia. In Achaia, Hybrida levied contributions on the province, an offence for which he was prosecuted by the young Julius Caesar in 76. However, he refused to appear and succeeded in escaping punishment after appealing to the people's tribunes.