The Hamilton Watch Co. produced a wide rage of military watches during World War II. These included variations on watches that were developed for civilian use as well as special purpose watches like the Model 22 navigational watch.
The Hamilton Model 23 Chronograph was the workhorse chronograph for all the U.S. military services during WWII. It was also the only complicated watch that Hamilton produced. It was incorporated into the design of the air navigation bubble sextant.
Using the 992B as the base model, Hamilton produced the model 4992B that incorporated a sweep second hand with a 24 hour dial. The 4992B was also made in a 12 hour variant for the British and Canadian (and later NATO) military services that was called the 3992B.
The watch called the 2974B was a 3 position 17J variant of the 992B. It provided a hack feature to make it particularly useful as a comparing watch, which is what it was called in the literature.
The standard 992B was also provided with government markings for military use, but identical to the civilian 992B in all other regards.
The Hamilton 3992B, issued to the Royal Navy as an HS3 deck watch, were all put into storage at Herstmoncaux Castle after WW2. Subsequently some of them were modified with a decimal dial that showed the 60 second period covered by the sweep second hand broken down into 100 divisions. The hour and minute chapters were smaller and of differing colours with matching hands. These were re-issued using the NATO Stock No 0552 521-0243 and the HS3 Deck watch code obliterated.
Some of these watches were also re-issued to the Royal Air Force in the 1960's, in their original form, for use as navigation aids on the long range aircraft of the day. This latter group were re-etched with the Air Ministry section & reference number 6B 60.
This article is a stub that needs to be expanded with images and more details on each of these models.