After the end of the roman republic, which instrument of government was no longer supreme?

The Senate

Explanation:

The end of the Crisis can likewise either be dated from the Assassination of Julius Caesar on 15 March 44 BC, after he and Sulla did so much "to dismantle the government of the Republic," or alternately when Octavian took on the name of Augustus and founded the Roman Empire in 27 BC.

lincoln presided over the union victory in the american civil war, which dominated his presidency. a former whig, lincoln ran on a political platform opposed to the expansion of slavery in the territories. his election served as the immediate impetus for the outbreak of the american civil war.