The Europeans visitors were technologically more advanced and, as it has been proven repeatedly, whenever a technologically advanced society makes contact with a primitive society, it is the primitive society that suffers.
As more Europeans continued to immigrate to the new world, they brought many new and strange ideas with them. Some were so strange and foreign that the Indian of the period simply could not countenance them.
For example, the concept of land ownership.
To an Indian of that period, everyone owned the land in common with everyone else. This was a given; a tenet ingrained into the very fabric of their collective culture. So that when they were approached to "sell" some prime real estate, they smiled at their foolish guests and agreed to accept some trade goods for land. In all likelihood, snickering among themselves at the stupidity of these whites. Imagine! Owning the land! I mean, who ever heard of such a thing? Really!
But the whites kept coming in their millions, swarming across the land like locusts, and rather than live in harmony with the land, as the Indian had done for thousands of years; the white man subdued it and bent it to his will. Too late, the Indian realized that the white man was serious about physically owning the land, and in his insistence on fencing it in to keep others away.
Naturally, this caused conflict between the Indian free-ranging hunter/gatherers and the white homesteader/farmers. The Indian was continuously forced back as the encroaching whites demanded ever more and more land. Treaties were entered into with the Indian and shamelessly broken repeatedly by the white man. Eventually, more sinister measures were taken.
But let's not delve into the cold-blooded, and calculated genocide our progenitors
perpetrated on the Indian during this period. Let us only say that the white man's
treatment of the red man during this period was reprehensible.
For those seeking additional background during this period, here is a historical timeline showing the advent of the Europeans and some of their depredations.
...and thus the stage was set for the Indian Wars, and the advent of one of its most notable generals and statesmen...