Marcus Licinius Crassus, Pompeius Magnus, and Julius Caesar met in Ravenna during March 56 BC to reaffirm their political alliance. The three men agreed to marshal resources for the upcoming elections of 55 BC. Their goal was a second joint consulship for Crassus and Pompey. Legislation passed by tribune Trebonius granted extended proconsulships matching that of Caesar in Gaul. Crassus arranged to receive Syria with the transparent intention of going to war with Parthia. This political overview derives from Erich S. Gruen's work on the Conference of Luca. The faction secured the consulship and most other offices sought through money and influence. Pressure took many forms including patronage and friendship. A force of 1000 troopers brought from Gaul by Crassus's son Publius added weight to their campaign.
Parthian Succession Crisis
A war of succession broke out in Parthia in 57 BC after King Phraates III had been killed by his sons Orodes II and Mithridates IV. In the first stage, Orodes emerged victorious and appointed his brother as king of Media. Another armed clash made Orodes force Mithridates to flee to Aulus Gabinius, the Roman proconsul of Syria. Gabinius sought to interfere in the succession dispute on behalf of Mithridates so Rome could make him its puppet king. However, Gabinius abandoned his plans and opted to intervene in Ptolemaic Egyptian affairs instead. Mithridates proceeded to invade Babylonia on his own with some initial success but was soon confronted by the army of the Parthian commander Surena. Crassus also sought to ally himself with Mithridates and invaded Parthia's client-state Osroene in 54 BC. He wasted most of his time waiting for reinforcements on the Balikh River's left bank while Surena besieged, defeated and executed Mithridates in Seleucia on the Tigris. Orodes, now unopposed in his own realm, marched north to invade Rome's ally Armenia.