I've done other posts on the subject in the past - so check out these posts for more information.
WWII "Tea-Cup" Watch
WWII Military Watches
US Navy "Canteen" Diver's Watch
Korean War USMC Watch
Hamilton's production was dedicated to the war effort during WWII. In fact, Hamilton also made watches for the Canadian and Russian military as well. Over the course of the 1940's, various contracts and enhancements resulted in a variety of very similar-looking watches being produced. For the US military, they generally were produced as follows...
- Army ORD DEPT OD 2 piece "snap" case aka the "tea cup" (Star Watch Case) 110,336 with 987A movements produced for the Army
- Army ORD DEPT screw case ("S" between the lugs Star Watch Case) 110,336 with 987A movements produced for the Army
- BUSHIPS Canteen Diver's Watch ("W" between the lugs Wadsworth Watch Case) with 987S movement. This is a truly waterproof case and the glass crystal is held in place with lead. The authentic strap is a flexible plastic. The correct hands are stainless steel.
- Navy BUSHIPS ("H" between the lugs Keystone Watch Case) with 987A. Dial has USN BUSHIPS printed in white and Hamilton in black just above it but it's hard to see. The back is engraved "USN BUSHIPS"
- Navy R88-W-800 27023 ("H" between the lugs Keystone Watch Case) - with 987A and similar to above but without the USN BUSHIPS on the dial and part number 27023 is engraved on the back. You can see the Hamilton in black on this dial.
- Navy R88-W-800 39108 ("H" between the lugs Keystone Watch Case) 22,410 987S movements produced for the Navy (black dial) with 987S movement
- USMC R88-W-800 39108 ("H" between the lugs Keystone Watch Case) 15,888 movements produced for the USMC (white dial) with 987S movement
- USMC FSSC 88-W-800 39102 ("W" between the lugs Wadsworth Watch Case) 2,926 18 jewel 2987 movements with white dials produced for the USMC
- Navy FSSC 88-W-800 39103 ("S"between the lugs Star Watch Case) 12,000 2987 movements with black dials produced for the Navy
- 1946 ORD case (Star Watch Case) with 987S movement. This case was introduced to replace the chrome plated case and is "parkerized", or specially coated, to prevent corrosion.
- USMC OF 1947 - 1954 (Star Watch Case) with 17 jewel 747 movement. Same parkerized case but a smaller movement ring to accommodate the smaller 747 movement and a tap 10 crown instead of tap 8.
- 980 "Bomb Timer" for the Fairchild Gun Camera (Keystone Watch Case)
Hamilton also provided watches for the Russian and Canadian Military
- 3,000 987A for the Russian Military
- 2,000 987S for the RCAF (Enamel dial with non luminous hands similar to the Hamilton Secometer)
But hopefully the information above is helpful to resolving the mystery behind Hamilton military cases.