An overcoat I would throw away, a vest I wouldn't. The overcoat is pretty much single purpose and it's heavy. The vest, however, is both an article of clothing and an extra set of pockets - pockets which are pretty easy to get at even when you have your traps on. It doesn't weigh down your knapsack, because you can carry it by wearing it. They're not that warm when you don't button them. It's also a reminder that you are a civilian for whom the war is a deadly interuption, not a regular who wants to soldier for 30 years. When the armies stripped down for spring campaigning, the men sent things home that they wanted but didn't want to carry. I'm sure any number of vests were mailed home in April, and, maybe, written for again in October.
Pine River Boys, Co I, 7th Wisconsin
"We're... Christians, what read the Bible and foller what it says about lovin' your enemies and carin' for them what despitefully use you -- that is, after you've downed 'em good and hard."
-Si Klegg and His Pard Shorty