With the outbreak of the American Civil War, he enlisted in the United States Army on May 18, 1861, at the age of seventeen, despite his parents' protests.

He was one of only six Union soldiers to be retroactively awarded the Silver Citation Star on the Civil War Campaign Medal for gallantry in action.

In 1871, while serving as a band leader in Buchanan, Michigan, Conn badly injured his hand while working at the local zinc horse collar-pad factory.

During this time, Conn sold health care products under the tradename "Konn's Kurative Kream",[1] and invented parts for sewing machines.

[2] In 1884, Conn organized the 1st Regiment of Artillery in the Indiana Legion and became its first Colonel, a military title which stayed with him throughout the remainder of his life.

The same year, during his congressional term, Conn bought the newly established Washington Times, and conducted a sensational campaign against alleged vice in the city.

After his term in Congress, Conn resumed the manufacture of band instruments at Elkhart, Indiana, while also investing heavily in other businesses.

The deed included, in addition to the horn factory, what was then known as the Angledile Scale Company, and The Elkhart Truth, some sixty descriptions of real estate in Elkhart and vicinity, various real estate mortgages, 125 shares of stock in the Simplex Motor Car Company of Mishawaka, Indiana, a seagoing yacht, a lake motor launch, and much valuable personal property.

Conn also lost considerable face when he was ordered by a judge to publicly apologize for publishing inflammatory comments about J. W. Pepper.

The Musical Courier picked up on the legal problems and reported about how Conn was knowingly making false statements about Pepper.

Conn authored books in his retirement, including The Sixth Sense, Prayer: Brain Cell Reformation (1916), For the Good of the World.