The 12th Maine Regiment, formed in November 1861, was one of the 10 regiments Major General Benjamin F. Butler of Massachusetts received permission to form. George F. Shepley a Democrat and a noted Portland lawyer and U.S. Attorney for Maine, headed the new regiment. On Oct. 1, 1861, Shepley wrote to Maine Gov. Israel Washburn to report that he expected the new 12th Maine Regiment to be filled soon "with the very best men in the State." Shepley also reported, "I have abandoned every other thought and pursuit, and have embarked in this movement all my hopes energies and efforts and, if need be my fortune and my life."
Accounts of engagements
;The 12th Maine in Louisiana According to the New York Times, "The town of Madisonville, La., on the other side of Lake Pontchartrain, has been captured without resistance and is now garrisoned by our forces. The expedition consisted of a portion of the Maine Twelfth, the Connecticut Ninth, two battalions from the convalescent camp of the Thirteenth Corps, the Massachusetts Fifteenth battery, battery of the United States artillery and a company of the Louisiana Second cavalry, the whole under the command of Col. Kimrall, of the Maine Twelfth. The 8th of January was observed by a salute at meridian by order of Gen. Banks. The great Union mass meeting was held here the same night at the St. Charles Theatre, which was crowded from pit to dome, including a large number of planters from up and down the river. Speeches were made by Messrs. Flandres, L. Madison Day, and Thos. J. Durant."
Significant events
;1861
November 16 Organized at Portland and mustered in
November 24 Unit left Maine for Camp Stevens, Mass.
December 30 To Boston
;1862
January 2 Embarked on Steamer Constitution for Ship Island, Miss.
February 12 Arrived Ship Island. Attached to Butler's Expeditionary Corps.
November 19 Non-Veterans left front. Veterans consolidated to a Battalion of four Companies.
December 7 Non-Veterans mustered out
;1865
January Ordered to Savannah, Ga.and attached to District of Savannah, Ga., Dept. of the South
February - March Six new Companies organized for one year service and assigned as E, F, G, H, I, K.
March Attached to 1st Brigade. 1st Division, 10th Army Corps, Army Ohio
;1866
February - March Companies E, F, G, H, I & K mustered out
The regiment was discharged from service on April 18, 1866.
Total strength and casualties
The regiment lost 3 officers and 49 enlisted men killed in action or died of wounds. 2 officers and 237 died of disease for a total of 291 fatalities from all causes.
"The oddest pets we have yet seen were two bears, which the 12th Maine regiment of the 19th Corps, led through the city recently. These bears were brought all the way from Louisiana, and have been in several fights. They have become perfectly tame and tractable, and march along at the head of the band, with an air that indicates they feel themselves veteran soldiers of the bruin order, and that they have a character to sustain."
