The ultra-thin quartz watch was created in the 1970s as a point of pride for Japanese, Swiss, and American watchmakers. Known as the thin-watch war, the period between 1978 and 1981 was a turning point for quartz technology, resulting in the production of a watch that was too thin to wear and thin movements that would dominate watch sales for the next decade.
Although Swiss, American, and Japanese companies developed and introduced quartz watch movements at the same time, the Swiss were slow to improve on their first designs. By the mid-1970s, Japanese companies were pulling ahead with thin, reliable quartz movements, while the Swiss were just developing their second-generation technology. This translated into sales, especially in America and Asia, and threatened the Swiss watch industry.
Citizen was first to market in 1978 with the Exceed Gold. The watch measured 4.1 mm thick, but the movement was under 1 mm, demonstrating what the company could do. Measuring just 0.98 mm, Cal. 790 would remain one of the thinnest watch movements ever made. It would remain the leading movement from Citizen for a decade. Cal. 790 was offered in a 2-handed gold-cased watch priced from 280,000 to 300,000 Yen (about $6,000 in 2020 US dollars). Citizen also offered a more practical movement, Cals. 7920 and 7930, which measured 1.95 mm thick and were twice as accurate, to +/- 5 seconds per month.
Seiko was also hard at work on an ultra-thin quartz watch. On July 20, 1978, Seiko showed their ultra-thin quartz watch, with Tiffany as a retail partner in the United States. Measuring just 2.5 mm thick, it was thinner than any previous watch and showed how far ahead the Japanese were. The movement, Cal. 9320, measured just 0.90 mm thick, with the New York Times noting that it was smaller than a dime.
Seiko priced the ultra-thin watch at US$5,000 and Tiffany announced the new watch with a full-page advertisement in the New York Times. A Seiko spokesman claimed in February 1979 that the company had sold 15 of the watches through Tiffany in the first six months of sales.
After the release of the Concord Delirium in early 1979 and the 1.5 mm Delirium II later, Seiko developed a thinner model of their own. Available in both LCD and analog versions, it measured 1.79 mm thick. The LCD version retailed for US$3,500, while the analog version was still $5,000. Seiko said they planned to produce 500 examples starting July 27, 1979, but later reports suggest that shipment did not start until October of that year.
In 1980, Seiko created a special Credor model for Japan with Cal. 6720, measuring just 0.89 mm thick. Seiko continued working on ultra-thin movements throughout the 1980s, though none were thinner than Cal. 6720 until the release of Cal. 9A85 in 1989, which was just 0.85 mm thick. This was used in the commemorative 20th anniversary quartz model, which was the highest-priced Seiko watch at the time at 1 million Yen.
American businessman Gerry Grinberg demanded that the Ebauches SA and their subsidiary ESA/ETA develop a world-beating ultra-thin movement before they lost the entire market to the Japanese. Grinberg had made a fortune building Piaget into a powerhouse for ultra-thin luxury watches but watched that market evaporate as Seiko and Citizen pushed quartz thinner than any mechanical movement. He offered CHF 2 million if ESA/ETA could deliver an ultra-thin 9 ligne quartz movement for use in a new line for his Concord watch brand.
On January 12, 1979, at press conferences around the world, Ebauches SA and ETA, together with Concord, Eterna, and Longines announced the world's thinnest watch. Measuring just 1.98 mm thick, the three manufacturers introduced remarkably similar watches. All were powered by the ESA Cal. 999, a thin watch movement built directly into the rectangular watch case. It had been developed in under 2 years and was built by Ebauches SA for all three brands. It was so thin it required the world's smallest battery; developed by ETA subsidiary Renata, Battery No. 32 measured just 6.8 mm diameter in 1.1 mm thick. The watch lacked a crown, using a push on the caseback to set the time and change the timezone.
The watch was branded Delirium, and this is the name used by Concord for their models, which were focused on the American market. Eterna called their version the Espada while Longines simply used the name, Quartz. Eterna and Longines also sold the Ladies model, called Delirium 2 by Ebauches SA, Linea III by Eterna, and Delirium III by Concord. The watch was extremely expensive and impractical, with some selling for over CHF 10,000, but showed the world that the Swiss could compete directly with the Japanese. Concord priced the Delirium at US$4,400 to better compete with the Seiko, but this did little to boost volume.
The ultimate Delirium model, and still the thinnest geared watch ever made, was the Delirium IV. Introduced in December 1980, this model used inscribed sapphire discs rather than hands and measured just 0.98 mm thick overall. It was too thin to wear.
ETA used the Delirium technology as the basis for the Swatch, introduced on March 1, 1983. That project was initially known as “Delirium Vulgare” (“Delirium for the masses”) with the movement similarly constructed directly into the back of the case. This would be the most lasting legacy for the Delirium project. Lead by the legendary ETA CEO Ernst Thomke, a small team of engineers (including Elmar Mock and Jacques Müller) and marketing consultant Franz Sprecher conceived of an inexpensive plastic quartz watch with fashionable colors and designs. Although the Delirium design was quite different from the Swatch, the former lead directly to the latter.
ETA also used the basic Delirium design to produce a standalone movement measuring just 0.98 mm thick. Longines used this as part of their Collections XL line in 1983. After this, only Concord continued to used the Delirium name. A 1988 redesign of the Delirium gained a crown for the first time, and this is present on all models after that date. Today, Delirium is a line of moderately-thin watches for Concord.
On March 19, 1980, Omega introduced their own ultra-thin quartz model. Cal. 1355 was integrated into the case back like the Delirium, resulting in a watch that was 1.35 to 1.48 mm thick. Omega pioneered the use of sapphire discs rather than hands in their thinnest models, the technique that allowed the Delirium IV to reach 0.98 mm thickness. The watch was developed jointly by SSIH in Bienne with assistance from their L'Orient, Geneva, and Sesto Calende factories.