I have read a lot about the American Civil War over the years. That reading has included every thing from scholarly works written by trained historians to the diaries and letters of the common soldier. I would venture to say that 90 per cent of the literature about the war touches, to some degree, the subject of foraging. All manner of edibles are mentioned including meat on the hoof, meat smoked, and meat salted. Fish and sundry other aquatic foods such as crab and oysters are much in evidence especially if an army is camped for an extended period near a river or along the coast. Of course vegetables are always mentioned, as are the fruits and nuts that grew in abundance in all parts of the divided nation. Even on rare occasion okra can be found as part of a foraging soldiers bill of fare along with the tubers Irish potatoes, sweet potatoes and yams. In all my recollection however, I do not recall ever seeing tomatoes mentioned. I wonder why?
That may be partially answered by the fact that the tomato is not one of the best traveling fruits to ever be harvested. It would be difficult for a forager to return with this item in good order to his mess. In the case of the long range foragers of William T. Sherman, it would be next to impossible. Those guys went for miles and other more sturdy items probably took first place.
Another answer may be that the plant was grown more as a decorative vine than as a food source so finding a plant laden with fruit may have been difficult and dependent on what time of the year the soldiers passed by. The vine may not have been in blossom yet or the fruit still green or even after the time of harvest.
Once upon a time, too, the tomato was thought to be poisonous, and if you ate one and survived you must be a witch! So superstition might have played a big part in the soldiers reasoning to pass this vegetable by. (The tomato was not declared to be a vegetable until 1893, by the US Supreme Court no less, although botanically it is a fruit.  This disagreement in itself may be why it is never mentioned. What hungry soldier would want to argue the point?)
It is just one of those questions that enter my mind from time to time as I research things relating to the war. It is inconsequential of course but haven't you ever been reading and have an “I wonder...” question enter your mind? Actually this question was one of those, popping into my head while enjoying a vine ripened tomato, the real deal not the hot house kind that are next door to eating wax.
It just seems to me that a big old tomato would sure perk up a chunk of salt pork and hardtack like it does the BLT sandwich or hamburger we all enjoy and it would have been worth jotting down in a diary or letter just to let the folks at home know the soldier was eating well enough. But then again if superstition was a factor, eating them may be cause for alarm to the homefolk.