In November 1864 a number of Union Ironclads were to be found on the James River in Virginia, supporting Federal ground operations there. A large number of the men on board the vessels of the James River Flotilla were Irish; indeed they made up an estimated 20% of all Union sailors. How did they and their comrades celebrate Thanksgiving 150 years ago?

Officers on the deck of the U.S.S. Onondaga with their dogs. The identity of the Irish correspondent, ‘Garryowen’, has not been established (National Archives).
We are fortunate that one of them has left us an account. He was a sailor on the U.S.S. Onondaga, one of the Union monitors on the James. Corresponding under the pen-name ‘Garryowen’, he wrote frequently to the New York Irish-American newspaper, who regularly published his letters. His account tells how the ‘sturdy sons of Neptune’ began their day by dispatching some unfortunate Turkeys, before their thoughts turned to loved ones at home. Thanksgiving ended with the sailors engaged in an altogether more deadly contest, as they took fire from a Confederate shore battery. ‘Garryowen’ takes up the story:

A view of the U.S.S. Onondaga on the James River during the American Civil War (Library of Congress).
U.S. Iron-Clad “Onondaga”, Dutch Gap, James River, VA., Nov. 28, 1864.
…We had our Thanksgiving Festival, and indeed the patriotic parties who were instrumental in getting it up are deserving of more than an ordinary share of praise for the creditable manner in which the affair was managed, as we received an abundance of Turkeys, &c., which made the berth deck resemble a poultry market on a small scale. After all being served the work of dissecting commenced; the cooks “pulled off their coats and rolled up their sleeves,” transferred the gobblers to the upper deck, and went through the process of immersion in the James with the said gobblers. On Thanksgiving morning the “galley” was the centre of attraction- roasting, baking, boiling, stewing, and all the pharaphernlia of the culinary department brought into requisition and under full headway. At the usual time, eight bells announced dinner, when there was a simultaneous attack on the enemy. Talk about storming the enemy’s works, and taking them by assault, but the attack on the defenceless gobblers throws Sherman’s flanking movements in the shade; for, in less time than it takes to tell it, they had all disappeared before the terrible onslaught of the sturdy sons of Neptune; and thus was fought the great battle of Thanksgiving on the James.

‘Having discovered a new iron-clad…they determined to give her a welcome’. The U.S.S. Mahopac on operations on the James River (Library of Congress).
Having this temporarily enjoyed ourselves, had we no thoughts of those dear, fond and loving ones at home- did the question occur to us, what kind of a Thanksgiving had our wives and little ones? Oh, yes! It could not be otherwise, though we felt somewhat consoled and assured that the same bountiful and patriotic hands that provided for us, would not see them want for their Thanksgiving festival, as no luxuries, no comforts, no encouragement is so acceptable to the soldiers or sailors as the assurance that our families are not neglected. Let us only hear that they are looked after and cared for, and no dangers, no risks or privations will be too much for us to endure or encounter; with a willing cheerfulness will we strike the foes, and with our strong right arm to the rescue, our once happy, united and prosperous country will again take her place among the nations of the world, a terror to traitors at home and enemies abroad.

‘…Mortar shells from Howlett’s Battery…’. The Confederate Battery at Howlett House which fired on the U.S.S. Onondaga and other Federal vessels on Thanksgiving Day, 1864 (Library of Congress).
In the evening, while we were congratulating ourselves on the happy events of the day, we received a salute from our pugnacious friends- the “Rebs.” Having discovered a new iron-clad- the “Mahopac”- they determined to give her a welcome in the shape of mortar shells from “Howlett’s Battery,” in which exercise they indulged to a considerable extent. Their shots were aimed mighty accurate- one of the shells having hit the “Mud Digger,” at the canal, in the ribs and sent her to the bottom. At this juncture we were called to quarters, and commenced firing a few of our 15-inchers, scattering terror and dismay among them, which soon caused them to cease their vomiting. For about two hours a brisk cannonading was kept up by both parties, which resulted in immense quantities of metal being wasted, and “nobody hit.” About dusk it was “all quiet on the James” again and remains so yet.
GARRYOWEN.

‘…Having hit the “Mud Digger,” at the canal, in the ribs and sent her to the bottom.’ General Butler’s forces were engaged in an ultimately unsuccessful project which involved digging a canal to try and bypass some Confederate batteries on the James. This photo is the dredge boat that ‘Garryowen’ witnessed sinking on Thanksgiving Day, 1864 (Library of Congress).
References
New York Irish-American Weekly 17th December 1864. Our Iron-Clads in the James River.