Interesting Swiss silver keyless lever chronograph Circa 1918

Silver chronograph made for the U.S. Army Corps of Engineers
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A fine and interesting Swiss silver open faced chronograph keyless lever pocket watch made for the U.S. Army Corps of Engineers, circa 1918. Frosted gilt movement, 20 jewels, straight-line lever escapement, cut bimetallic compensation balance, blued steel Breguet balance spring, swan-neck micrometre regulator, visible chronograph works, chronograph button on the winding crown. Hinged silver cuvette. White enamel dial with luminous bold Arabic numerals, outer chronograph divisions, sunk subsidiary seconds dial and original luminous blued steel skeleton hands. Solid case, polished. Dial, case and movement signed, case numbered.
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Diameter: 52 mm
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Signed: Vacheron & Constantin Genève
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The U.S. Army Corps of Engineers history can be traced back to June 16, 1775, when the Continental Congress organized an Army with a Chief Engineer and two assistants. Colonel Richard Gridley was to become General George Washington’s first Chief Engineer. It was not until 1779 that Congress created a separate Corps of Engineers. The Corps of Engineers has been instrumental in all U.S. military actions since this time; from the American Revolution where, with the assistance of several French officers, they were a key component in battles such as Saratoga and the final victory at Yorktown, up to today’s actions in Iraq. The Corps of Engineers has also from the beginning been charged by the U.S. Congress with construction and works ‘of a civil nature’. Throughout the 19th and 20th centuries, the Corps of Engineers has overseen the construction of coastal fortifications, lighthouses, dams and other heavy engineering projects, as well as developing jetties and piers for harbours. The Corps was also responsible for the vast majority of the American West’s mapping in the 19th century, as well as mapping of U.S. navigational channels. Due to the Corps’ requirement for a robust and accurate chronograph to be used during various activities, the head of the U.S. Expeditionary Force in Bern requested that Vacheron Constantin produce a prototype for field use. The watch was to have a silver case, a white dial with luminous Arabic numerals and hands, and a simple chronograph movement without counter. Vacheron Constantin produced two prototypes that were delivered on May 8, 1918, an order for 5,000 pieces was placed that same day. The original order was to be delivered in lots of 100 watches per month, 150-200 whenever possible. From July 1918 through late 1919, a total of 3,289 watches were delivered, and the contract was deemed to have been met. Vacheron Constantin archives indicate that the firm also made wristwatches with silver cases and gold buckles for the Corps of Engineers.