Final answer:
The first war involving Native Americans was Metacom's War or King Philip's War, which is also considered one of the most violent due to its high casualties relative to the population.
Step-by-step explanation:
The first war involving Native Americans was Metacom's War, also known as King Philip's War (1675-1676), which was a fierce conflict between New England colonists and the Wampanoag tribe. Regarding the most violent war involving Native Americans, many historians consider King Philip's War to be among the most brutal due to the high number of casualties relative to the population. This war resulted in devastating impacts on both the indigenous populations and the colonial settlers. The early period of American colonial history was marked by a series of conflicts where Native Americans were often central figures. In these conflicts, the struggle over land and resources was a common theme, leading to significant violence and upheaval.