Both Byzantine Empire and Rome were all Christian country. But they had different version of Christianity. For example, Romans thought Roman pope was the head of Christians in the world, but the people of Byzantine didn't think so. They had their own head of Christianity
The Navigation Acts lead to the American Revolution, as it was another way that Great Britain was unfairly controlling the colonies and their economy. The Navigation Acts were that the British colonies were unable to trade with foreign ships, such as Dutch, French and Spanish ones and only Great Britain was able to trade with these countries. The British said this was intended to protect the Americas from being reaped of their gold and silver, but it was just another control policy. This pushed the colonies to vouch for the American Revolution to get rid of British rule.
Military development wasn’t all that advanced in the 1800s, also expansionism and uprisals from colonies were the major cause of war. Also, war tactics were not as aggressive or debastating.