1946 Jaeger-LeCoultre 12A "Bumper" Military

At the end of the Second World War, the mood was geared towards reconstruction, efficiency, and pragmatism. Jaeger-LeCoultre turned its inventive genius to the area of automatic round timepieces, forerunners of the Master Control line. The firstborn housed a Jaeger-LeCoultre 476 Calibre, driven by a ‘bumper’ type weight.”

The movement used in this watch is Jaeger LeCoultre calibre 476 (12A). The Calibre 476 was the first automatic movement from Jaeger-LeCoultre. Introduced in 1946, the Calibre 476 came 20 years after John Harwood and Blancpain presented the first automatic wristwatch. It boasted a respectable 40 hours power reserve and was accurate enough to be certified a chronometer 12 years later, in 1958. For those unfamiliar with the term "Bumper" Movement, this describes the system of self-winding where, rather than having full 360 degrees of rotation as was later introduced, the watch is wound by means of an oscillating rotor that is only allowed to travel through 180 degrees, being arrested by buffer springs that then bounce the rotor back in its original direction. These movements are enormously charismatic and when in use, the wearer can actually feel a distinct bumping sensation as the rotor hammers back and forth to wind the watch.