Born in 1836 in Troy, New York, and orphaned at ten, Hubbard first worked as a tinsmith in the east and then in Chicago.

During the American Civil War, Hubbard joined the Union Army in 1861 as a private in the 5th Minnesota Volunteer Infantry.

After the war's end Hubbard returned to Red Wing, where he simultaneously engaged in milling and railroading.

Hubbard forcefully urged government intervention in public health, corrections, charities, railroads, agriculture, and commerce, and the legislature complied by increasing the state's regulatory and licensing powers.

When America declared war against Spain in 1898, President William McKinley appointed the 62-year-old as a brigadier general of volunteers and asked him to oversee a military post in Florida.