Final answer:
President Ulysses S. Grant was most responsible for the U.S government's policy toward indigenous people in the late 1800s, as he had the overarching authority and influence on the policies toward Native Americans, even though figures like Henry Dawes and General Nelson Miles also played roles.
Step-by-step explanation:
When considering who was most responsible for the U.S government's policy toward indigenous people in the late 1800s, the most notable figure is President Ulysses S. Grant. President Grant had a significant impact on Native American policy with his intent to encourage a humane treatment of the indigenous populations and leading them toward citizenship.
Despite his intentions, the policies often resulted in violence and were less successful than hoped. Other individuals like Henry Dawes and General Nelson Miles played roles in Native American policies, but Grant, as President, had the overarching authority and influence on the United States’ policies toward Native Americans.
Grant's successor policies often followed his lead or were reactions to the circumstances created during his tenure. Therefore, while other figures such as Henry Dawes, William Tecumseh Sherman, and General Nelson Miles were involved, President Grant was the chief architect and thus most responsible for the policies towards Native Americans during that era.