Answer:
101 BCE: Gaius Marius was elected consul.
Step-by-step explanation:
Gaius Marius was the Roman general who was elected to be consul of the Roman Republic seven times. His first election was in 107 BC, while in 101 BC he was re-elected for the fourth time.
From all the events on the timeline, this is the one that happened earliest. Julius Caesar became dictator in 47 BC which was 54 after Marius was re-elected. The other two events happened in the common era, which means they were even later.