"Ease" in taking over Indian territories was not a term that readily came to the minds of the participants in various bloody conflicts with Indians. They fought back, often effectively.
The inglorious Second Seminole War in Florida, for example, lasted seven years (1835 to 1842) and included the "Dade Massacre" in which Major Dade's and his command of a little over 100 men were almost entirely wiped out. During that conflict, Indians attacked white settlers as far north as Tallahassee.
And then they got beaten back. You will notice that today Florida is in the hands of the Old World people, as is Wyoming, Montana, Minnesota, etc.
EASE is the term.