Rusk started his service with the Union Army during Civil War as major of the 25th Wisconsin Volunteer Infantry Regiment on August 14, 1862.

[3] He took command of the regiment on July 22, 1864, when Colonel Milton Montgomery was wounded and captured at Decatur, Georgia during the Battle of Atlanta.

[6] His most noted act during his governorship was when he sent the National Guard into Milwaukee to keep the peace during the May Day Labor Strikes of 1886.

The strikers had shut down every business in the city except the North Chicago Rolling Mills in Bay View.

This led to the Bay View Tragedy, in which a number of workers were killed; Governor Rusk took most of the blame.

In 1889, after the end of his third term as governor, he accepted the new cabinet position of secretary of agriculture in the Benjamin Harrison administration.

Later that year, Rusk married Elizabeth Marie "Berthe" Johnson, with whom he had four more children, though one died young.