It was not necessary to "advance civilization" by banishing Native Americans from their homeland, to a new, designated land for natives.
The Trail of Tears displaced more than 100,000 natives of the "Five Civilized Tribes" (Cherokee, Chickasaw, Choctaw, Creek, and Seminole).
The physical trail included five thousand miles of rough terrain.
The indigenous peoples reactions to the Indian Removal Act of 1830 varied. Nations such as the Choctaw and the Chickasaw signed an initial agreement relatively early, and were finalized within a year or two. However, the Creek Nation's journey was delayed due to fradulent land sales. The Seminoles protested the removal; federal authorities were met with fierce resistance from the Seminoles. This ultimately lead to the Second Seminole War. Lastly, the (Southeast) Cherokee Nation sought legal action. Their lawsuits included Cherokee Nation v. Georgia, and Worcester v. Georgia. Around 1838, the Cherokees were forced out of their homes, some were even held in internment camps.
I would imagine that the militia was just as frustrated as the natives were, for the set backs, the resistance, and etc.