The history of armed conflicts involving the United States of America spans a period of more than four centuries. A period ranging from the early era of European colonization and the formation of the new national polity that would become the United States, to its evolvement through technological and political upheavals into a decisively modern republic and military force, and ascent onto the world stage, through the calamities of the 20th century, as the largely unrivaled hegemon that it is today.