Answer:
The United States President
Explanation:
This is the role that most resembles that of the magistrates during the Roman Republic. During this time period, two magistrates were elected for one year at a time to serve as both chief executive and military commander-in-chief. This is similar to the role of the president of the United States. The president similarly is considered to be chief executive. He is also the leader of the Armed Forces, as the commander-in-chief.
