Zenith opted for a more complex route than simply attaching a chronograph module to an existing movement. Their vision was to craft a chronograph that was seamlessly integrated into the movement, utilizing a column wheel for activation instead of the simpler cam mechanism. Moreover, they aimed to achieve an unprecedented level of precision, with the chronograph's frequency high enough to measure time to 1/10th of a second, setting a new standard for accuracy in wristwatch chronographs. The design also called for a compact size and the inclusion of a date function.
On January 10th, 1969, Zenith held a press conference to announce the upcoming release of their revolutionary movement. Originally known as the 3019 PHC, this innovative creation was later named “El Primero”, translating to “the first” in Spanish, a fitting title for a movement that marked a significant first in the history of watchmaking.