It is a myth that the Marines had leather collars in the Phillipines. No photographic evidence or written accounts of this happening exist that I know of. It isn't in any history of the Marine Corps that I've ever read. When I was in the Marines, this wasn't the lore that was taught.
Its a MYTH. Let's dispel it.
Think about it...are you going to tell a bunch of Jarheads to wear leather collars in the heat of South East Asia in order to protect their necks against BARONGS? Those things will take off hands, arms, legs, and cleave through the top of heads from the eyebrows up. Why wear that ONE piece of armor?
Heck, the Marines would be ripping them off. Can you imagine anything more uncomfortable in that humidity...and on patrol in the jungle? Gad.
"Marines fighting in the Philippine (sic) Insurrection...usually wore the soft field hat, khaki trousers and leggings and blue wool flannel shirts. Wool flannel, once soaked with sweat, was thought to be cooler than cotton. Mustard-colored flannel shirts came later and sere worn by Marines as late as the Korean War."
--The Marines
Edwin Howard Simmons, Editor in Chief
J. Rober Moskin, Editor
Marine Corps Heritage Foundation
Page 142 (photo caption)
The same book gives the time period of the leather collar being worn the Continental Marines.
The term "leatherneck" is discussed here:
http://www.southcoastsar.org/Leathernecks.htm
http://www.mcu.usmc.mil/ftw/files/lore63.txt
The stock collar was largely for dress purposes, was dropped after 1859, and never used again.
Ever the gadfly,
Steve Scott