Leader of Roman nobility who tried to block Julius Caesar's rise to political power.  As Caesar's co-consul in 59 BCE, Bibulus vetoed Caesar's bill designed to distribute land south of Rome to Pompey's troops. The popular Assembly reacted with mob violence, symbolically driving Bibulus from office & leaving Caesar's edicts unchecked for the rest of his term.  

Bibulus was eventually able to avenge that disgrace, as the rivalry between Pompey & Caesar deepened.  After the murder of Pompey's co-consul [Publius Clodius] in 52 BCE, Bibulus persuaded the Senate to allow Pompey to complete his term without choosing a peer. The following year he was rewarded with appointment as governor of Syria.  Other than some tension between Roman troops in Syria and their new commander, who claimed credit for the legions' victories over the Parthians under his predecessor [Cassius], Bibulus' term in this post passed without major incident--in dramatic contrast to the political turbulence elsewhere in the Mediterranean at this time. 

Early in 48 BCE he succeeded in stranding Caesar's forces in Epirus [modern Albania] by capturing his transport ships in the Adriatic.  But this minor victory was erased a few months later by Caesar's crushing defeat of Pompey at Pharsalus, an event Bibulus had the misfortune of living just long enough to witness.

References: Suetonius, Twelve Caesars: Julius Caesar 9-10, 19-21.
                   Cassius Dio, Roman History 37.8; 38.4, 6, 8; 40.30.
                   Livy, History of Rome [summary 108].
                   Appian, Roman History: Civil Wars 2.9-12, 49; 5.10.

Other resources on line:

• Marcus Calpurnius Bibulus - entry in Wikipedia's web.