Interesting Swiss silver chronograph pocket watch Circa 1918

Silver watch made for the U.S. Army Corps of Engineers
–
An interesting Swiss silver keyless pocket watch with a chronograph, circa 1918.
A polished case, hinged silver cuvette. White enamel dial with bold upright Arabic numerals, outer Arabic minute and chronograph ring and subsidiary seconds and blued steel skeleton hands. A frosted gilt brass movement, 20 jewels, straight-line lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring, swan-neck micrometre regulator, chronograph with visible work, and the button on the winding crown. Dial, case and movement signed.
–
Diameter: 52 mm
–
Signed: Vacheron & Constantin  Genève
–
The case and movement are both slightly scratched, and the movement is also oxidized.
The dial is spotted and there is some damage on the hands.