William Lowell Putnam served in the 20th Massachusetts Infantry Regiment. He died on 22 October 1861 of wounds received at the Battle of Ball's Bluff.
After Putnam's death, the Rev. James Freeman Clarke eulogized "the boy soldier" as a "pure soul sacrificed in a struggle with evil." Lt. Putnam, an ardent abolitionist, had died nobly "not for country alone, but for humanity." Two additional carte de visite photographs held by the MHS can be viewed here and here.