If the old Veteran that told me about this knew why, I don't remember him telling me why. Over the centuries of wars military equipment I believe has been "dumped" in every war. Why does the government do a lot of things and not needing a reason. This is my thought on the dumping of horse equipment at the end of WWII. To relieve crowding on the ships and even though the horse cavalry equipment was new, it was deemed antiquated and the first and easiest to be cast overboard.