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With all these requirements, the bar was raised so high that the project could not be completed in time for the centenary in 1965 but it required four more years.

A relatively small size and a date indication were additional specifications. And to make things even more challenging, the beating frequency of the chronograph had to be high enough to make it the most accurate chronograph wristwatch in the world measuring 1/10th of a second. Instead of considering the easier option to add a chronograph module to a base movement, Zenith had a more ambitious plan: the chronograph function had to be fully integrated within the mechanism and actuated by a column wheel rather than by an easier-to-implement cam. In 1962, Zenith began developing the idea of creating the first automatic chronograph in watchmaking history with the ambition to launch it in 1965, on occasion of the centenary of the Manufactury.

While automatic movements for “solo-tempo” or three-hand watches started becoming popular in the 1940s and 1950s, no automatic chronograph movements had been manufactured yet.

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