He was a member of the Wisconsin State Senate from 1899 through 1902, representing Manitowoc and Calumet counties.
At the outbreak of the Spanish–American War, he volunteered for service and was mustered as first lieutenant of Company H in the 2nd Wisconsin Infantry Regiment.
[2][3] With the 2nd Wisconsin Infantry, he participated in the Puerto Rico campaign and commanded Company H throughout the war, due to the sickness of his captain, William Abel.
Knudson prevailed in a close general election, defeating Democratic candidate John P. Watt by just 37 votes.
After his time in the Senate, he moved to Atlanta, Georgia, to work for a lumber company.