Final answer:
Caesar's dramatic action before fainting was crossing the Rubicon River, which led to him being declared a dictator and was perceived as tyrannical, ultimately resulting in his assassination.
Step-by-step explanation:
Before Julius Caesar's fainting in front of the people, he took the drastic and momentous action of crossing the Rubicon River in 49 BCE, which was a clear act of sedition against the Roman Republic. This marked the start of a civil war against Pompey and the conservative faction in the Senate. Caesar's march on Rome with his army was both an assertion of defiance and a symbolic gesture, indicating a point of no return as he is reputed to have declared, “the die is cast.” He positioned himself as not just a military leader but as a protector of the common people against the corruption of the Senate, promising to defend the legal rights of himself and his troops. The culmination of these events led to him being appointed dictator, initially temporarily, but then for an indefinite period and eventually for life, which consolidated his power but ultimately sowed the seeds of his assassination in 44 BCE. Despite his attempts to stabilize his rule by including former enemies in the Senate and government, his actions were perceived by many as tyrannical, leading to his assassination by members of the Senate, including Brutus and Cassius.