Which European country experienced a Civil War that created the conditions for the next global conflict?

How might the first nations have reacted when they saw that the europeans were moving onto their lands and disrupting their way of life? (this was when the europeans came to canada and tried to claim land to themselves)

How did roman authorities treat conquered peoples? required them to pay taxes to rome replaced their local governments compelled them to adopt roman customs invited them to become roman citizens

What is one example of trench warfare ?