What experts do historians rely on to provide accurate information about the connection between an aritifact and the culture or civilization it belongs to

According to some historians which marks at the beginning of the us civil war

This civil war battle took place in northwest georgia in september 1863, and, following over 30,000 casualties in just two days, resulted in a confederate victory.

1. how did manifest destiny spur nation building in the u. s.? 2. how did the idea of “the nation” begin to change? 3. how were the unifications of germany and italy similar? 4. what problems did the austro-hungarian empire have? 5. what domestic issues did england and france have?