In 1969 watches with three different automatic chronograph calibers were released to the public. Zenith was the first company to announce their achievement, but was last to deliver watches to the market for public sale. Heuer (in consortium with Breitling, Hamilton and Dubois-Depraz) announced at the April Basel watch fair and attempted to prove they were first, by giving samples of their watches to the attendant press and they were second to deliver watches to the market for public sale. Unfortunately their early caliber 11 watches suffered from overbanking and many were returned to the factory to be fitted with parts to correct the problem and stamped with an "I" under the balance. Seiko never announced their "achievement" as they were too busy announcing the quartz watch, but the presence of watches with their 6139 caliber with February 1969 production dates, demonstrates that while Heuer et al and Zenith were still working on finishing the development of their watches for production, they were in full production. Seiko was also first to market for public sale. You can expect Zenith to celebrate it. The El Primero's claim to being the first was pretty much built entirely on marketing. Heuer (ne TAG) has a claim, but since 1969 hasn't really marketed around their achievement for years. It is also hard to market around something you share with Breitling and Hamilton. Seiko, the tree that fell in the forest when no one was there to hear it, has never marketed around their achievement, so it would be strange to market around it now. Maybe the Zenith sub forum folks will discuss this topic in their area. Lacking a Seiko sub forum, the topic is presented here for discussion.