Quote Originally Posted by IsleGuy57
Neck stocks, as worn by British Redcoats in the Napoleanic era were high, tight collars of stiff leather. Their purpose was to cause the soldier to have a proper "military posture, ie: head high, not turning about". These items were so high and tight that they constantly left red marks from chafing on the soldiers necks. This is only part of the reason they were so detested. In addition, they were only worn by the common soldier. Never was there an officer that wore one... Hope it sheds a little light.
Concur with IsleGuy57. Neck stocks were not intended to ward off sabre blows. Remember, a well delivered blow can hack off a man's arm (read about a Russian who lost his arm that way during the Crimean War). Rather, like IsleGuy57 says, it was to "help" the solider maintain his soldierly appearance and bearing.