I hope that you are having (or that you had) a nice Thanksgiving, Gentle Reader. Please spare a moment from your day of food (and football) to think of those men and women in the Armed Forces who are away from home on this day, with a special thought to those on the ground in Afghanistan and Iraq, and those who are sailing into uncertain waters off the Korean Peninsula.
I've spent a Thanksgiving or two at sea, it's not terribly uncommon in the Navy. If the cooks are halfway good, the meal is a feast like none other (though cigars and cigarettes were no longer provided). It was a good idea to reflect on one's underway watch rotation before sitting down to eat, as showing up for watch ready to fall asleep from overeating was not a good idea.
On larger ships, a VIP might show up to thank the crew. A DoD or USO entertainment group might perform, which resulted in a sort of "mandatory fun" if not enough sailors showed up to watch the show. Smaller ships were luckier, usually they got to be on their own. Unless it was truly wartime, Thanksgiving was a day of holiday routine; no work was done other than sweepers, watchstanding and cooking. Everyone could sleep in if they didn't have to be up.
I was surfing around, saw the usual press releases, and found this Plan of the Day from a warship's Thanksgiving thirty years ago. (Scroll down until you see the first typed image and then click on it.)
I don't know the story behind it, but it sounds as though the USS Joseph Hewes had to leave for Thanksgiving to cover something that the USS Sellers was supposed to do. Probably one of the crewmen, or more than one, wrote that poem. If I remember correctly, only line officers could qualify for surface warfare pins back then, so it is possible that one of the wardroom rats had a hand in that.
Covering another ship's commitments was a bittersweet thing. The bitter was that it meant more time away from home. If it was over a holiday, your plans, the plans of your shipmates and everyone's families were ruined. The sweet was that there was considerable unit pride in being on a ship that could be told, on very short notice, to get underway and do someone else's job.  That was a hard thing to sell to one's family, but it was still true. The reverse was that the waterfront reputation of a ship that was indeed "welded to the pier" was not good. The higher-ups in the squadron and the group could be counted on to lavish the sort of extra attention on that short of ship which nobody on that ship relished receiving.
 If the cooks produced a terrible Thanksgiving meal, that may result in the Supply Officer and the chief cook getting fired.
 "You will attend and you will have fun."
 Between deployments, exercises and in-port duty days, it was common to sleep in your own bed maybe 60-70 days a year.
 I have no doubt that copies of that POD were mailed to the USS Sellers.
4 hours ago