Pingree was a Union Army veteran of the American Civil War and received the Medal of Honor for heroism at the 1862 Battle at Lee's Mills.

Pingree took part in numerous battles, and in 1891 received the Medal of Honor for heroism at Lee's Mills while commanding Company F in 1862.

[1][a] He received his early education in Andover, New Hampshire, and McIndoes Falls, Vermont, then entered Dartmouth College, where he graduated in 1857.

[2] He was severely wounded at the Battle at Lee's Mills on April 16, 1862, during which he led his company and three others across a wide creek and drove the enemy from rifle pits on the opposite bank.

[2] In addition to losing his right thumb, Pingree contracted typhoid; reports of his death appeared in Vermont newspapers, but were quickly corrected.

[2] During the second day of the Battle of the Wilderness, Pingree was placed in command of the 2nd Vermont Infantry, since all the field officers of that unit had been killed or wounded.

[2] Pingree participated in the battles of Spotsylvania, North Anna, Cold Harbor, Petersburg, and Weldon Railroad, where he narrowly escaped capture with a portion of his command.

[2] Pingree was an active member of the Windsor County Republican Committee and attended numerous local and state party conventions as a delegate.

"[13] During his gubernatorial term, Vermont took steps to conduct oversight and examination of the state's banks and expanded regulation of insurance companies by requiring them to submit annual reports and financial statements.

[16] During his term Pingree also advocated laws prohibiting the adulteration of maple syrup and honey, which unscrupulous operators had begun to dilute with beet sugar and other less expensive fillers.

[2] He was active in the Grand Army of the Republic and also served as judge advocate of the Medal of Honor Legion, an organization established in 1890 to protect the reputation of the award.