The judicial branch has the power to declare actions unconstitutional. Hope this helped!
The effect of foreign conflict on Americans support would be the War of 1812 where British captured Washington, D.C. and burned our White House, and also U.S. forces turn back a British attack on Baltimore. The good thing that came out of the conflict was gaining our "Star Spangled Banner" from Francis Scott Key.
It really depends on which era, if the question asks about the Roman Republic, then it would be a republican government. In Ancient Rome, an aristocracy was used. In the Roman Empire, the emperor was the main man, but he also had a senate.
Hope this helps...
Civilization in China began at the Yellow River Valley.