Initially, Palfrey was a first lieutenant in the 4th Battalion of the Massachusetts Militia. Not long after, he was made a lieutenant colonel in the 20th Massachusetts Volunteer Infantry, known as the "Harvard Unit" due to the number of graduates in this group. He would serve under
William Raymond Lee, and alongside
Henry Livermore Abbott,
Oliver Wendell Holmes Jr., and
Paul Joseph Revere. He was severely injured at the
Battle of Antietam. Following Lee's discharge in December 1862, Palfrey was promoted to Colonel of the unit, a rank he would hold until his own discharge in April 1863 due to lingering health effects. He married Louisa Caroline Bartlett on March 29, 1865, and they had three daughters. On May 4, 1866,
President Andrew Johnson nominated Palfrey for the award of the honorary grade of
brevet brigadier general, to rank from March 13, 1865, for gallant and meritorious services during the war, The
U.S. Senate confirmed the award on May 18, 1866. In 1872 he was appointed register in bankruptcy. He published
A Memoir of William F. Bartlett (1879);
Antietam and Fredericksburg, in the "Campaigns of the Civil War Series" (1882); and contributed to the first volume of
Military Papers of the Historical Society of Massachusetts and to the
North American Review. ==Other family==