Why were the Dakota Reservation and the Town of Mankato important locations during the War of 1862?

it was mainly located in Mankato, Minnesota

Explanation:

a conflict between the United States and several bands of Dakota. It began on August 17, 1862, along the Minnesota River in southwest Minnesota, four years after its admission as a state. Throughout the late 1850s in the lead-up to the war, treaty violations by the United States and late annuity payments by Indian agents caused increasing hunger and hardship among the Dakota. During the war, the Dakota made extensive attacks on hundreds of settlers and immigrants, which resulted in settler deaths, and caused many to flee the area. This ended with soldiers capturing hundreds of Dakota men and interning their families. A military tribunal quickly tried the men, sentencing 303 to death for their crimes. President Lincoln would later commute the sentence of 264 of them. The mass hanging of 38 Dakota men was conducted on December 26, 1862, in Mankato, Minnesota; it was the largest mass execution in United States history.

an informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.