Hubbell entered army service at
North Stonington, Connecticut. Captain Hubbell served in Company A of the
21st Connecticut Infantry at the
Battle of Chaffin's Farm. In that battle on September 30, 1864, at
Fort Harrison,
Virginia, he led out a small flanking party, engaged a
Confederate force and at great risk captured a large number of prisoners. For this action, Hubbell was awarded the Medal of Honor on June 13, 1894. He was discharged in July 1865 as a captain and brevet major. ==Medal of Honor citation==