Law I guess I really don't understand
Ans: Nationalism lead people to conflict. Archduke Franz Ferdinand was assassinated due nationalism by the Black Hand, a nationalist group that intended to liberate the Serbs from the Austro-Hungarian occupation. The death of Franz Ferdinand was one of the most important factos to cause the World War I.
They attacked enemy ships, passenger ships, and trade ships. Basically any ship they saw, they attacked it.
The United states has a federal system of government because power is shared between the central and state governments.