Military Watches of the World: Japan

We continue our survey of military watches by country in a visit to the Land of the Rising Sun, examining the rise of the Seiko company and its outsized role in the history of the Japanese military timepiece.

The history of Japanese watches produced domestically for military issue largely ceases in 1945, for the simple reason that Japan was deprived of the right to maintain military forces by the instrument of surrender signed in that year. Though the Japanese Self-Defense Forces (JSDF) has since become a sophisticated, powerful military and steadily increased its mission beyond domestic peacekeeping, this expansion of power began in the late 20th and early 21st centuries — largely after the heyday of the issued military watch.

19th Century

Western-style clocks made using verge escapements were originally introduced to Japan by Jesuit missionaries in the 16th century or Dutch missionaries in the 17th century. At the time, Japan utilized a lunar, temporal timekeeping system that divided the day into six daytime units and six nighttime units that varied in length according to the length of the seasons. This system, when combined with the isolationist foreign policy that had been in place since 1641, would prevent the adaptation of western timekeeping and technologies for some two centuries. It wasn’t until 1872, several years after the Meiji Restoration, that Japan adopted the western solar calendar, leading to the establishment of a modern clock industry.

Edo Period Clock (Via Le Musée Paul Dupuy)


In 1881, a 21-year-old entrepreneur named Kintaro Hattori founded a clock and watch repair shop in central Tokyo. Eleven short years later, in 1892, he opened manufacturing facilities for a company that he called Seikosha, from the Japanese seiko, meaning “exquisite,” “minute” or “success,” and sha, meaning “house.” After expanding his clock and pocket watch business throughout the 1890s, Hattori managed to see the proverbial writing on the wall and embarked upon the creation of his first dedicated wristwatch, which debuted in 1913 under the “Laurel” name. 

Laurel dial (Credit: Seiko)

This early “wristlet” featured a white porcelain dial, Arabic, Breguet-style numerals, wire lugs, an onion crown and a red “12,” a feature seen on many trench watches (and especially on “marriage watches,” or pocket watch conversions) that may have helped the wearer to quickly orient himself when glancing at the dial. The Laurel, which has all the hallmarks of a European WWI-era trench watch, appears to be a military design made for use by Imperial Japanese forces — perhaps exclusively by officers — but little detailed information on the watch is available.

The Great Kanto Earthquake of 1923 destroyed Seikosha’s facilities. After rebuilding, the company introduced the first wristwatch featuring the Seiko name on the dial in 1924, which would later feature on the company’s dedicated military watches during the Second World War.

World War II

Military watches produced for issue to or use by Japanese troops were manufactured by Seikosha, which by 1938 was capable of churning out 1.2 million timepieces per year. Due to its size and power, the company appears to have been the sole Japanese watch manufacturer with dedicated military contracts for wristwatch production during the war, though the scarcity of raw materials meant that much of the firm’s production was likely relegated to on-board instruments for aircraft, ships, etc. Unlike the Germans, who utilized both domestically produced specialist military watches and timepieces from the Swiss, who maintained neutrality during the conflict, the Japanese were isolated in the Pacific, and thus couldn’t easily be supplied with imports of foreign timepieces. 

Three Seikosha Military Watches (Credit: Seikoholics)

The rough Japanese equivalent of something like the A-11 — the iconic infantryman’s watch of the American forces — was a small, handwound timepiece housed in a ~30mm case, generally chrome-plated. Produced in three iterations for infantry, naval forces and pilots, these watches featured a white dial with black Arabic numerals, an inner, 24-hour track in red, sub-seconds, the Seiko name, and one of three “logos”: a star for ground forces, an anchor for naval forces, and a cherry blossom for air forces. While the ground and naval force models featured blued hands, the variant made for aviators featured radium-filled cathedral hands to enhance visibility during night-time operations. (Another variant occasionally pops up on the secondary market that appears to feature a stainless steel case, but this may be a later recase, as stainless steel is a war-critical material that likely wouldn’t have been dedicated to general wristwatch production.)

The Tensoku

Perhaps the best-known Japanese military watch of WWII is the Seikosha Tensoku, an abbreviation of tentai kansoku, meaning “astronomical observation.” First produced around 1940, the Tensoku is a sort of Japanese analog of the famed German B-Uhren, the aviator’s watch made for the Luftwaffe by five German and Swiss manufacturers. Housed in a massive 48.5mm, nickel-plated case case, the Tensoku featured a black dial with white Arabic numerals coated in radium, an outer, 60-minute track with red hash marks and Arabic numerals at 5-minute intervals, white, radium-coated hands, an oversized onion crown, and a coin-edge bezel. Clearly designed with visibility and ease of operation in mind (the oversized crown allowed an aviator to manipulate the watch with gloved hands), the Tensoku appears to have been produced exclusively by Seikosha in two variations: one featuring a 19 ligne, 15-jewel handwound movement, and a later model that utilized a nine-jewel handwound movement. 

Seiko Tensoku (Credit: Philips)

Fixed lugs necessitated the use of a leather strap — likely a two-piece that wrapped around the lugs and was held in place by a flexible metal tab, or was simply sewn in place. 

It is commonly accepted that so few of these timepieces survived the war because of their use by kamikaze pilots during suicide missions, but this association is tenuous and not well-documented. It does seem likely, however, that the watches were indeed used by pilots of the famed Mitsubishi A6M Zero, which formed the backbone of the Japanese aerial attack forces in the Pacific theater. Information on production numbers of the Tensoku is difficult to come by, and very few of them indeed appear to have survived the conflict. When they do surface on the secondary market, prices reflect this scarcity.

Photos of Japanese flight crews from the war show many pilots and navigators wearing pocket watches suspended from cords around their necks. Seikosha, which had been manufacturing pocket watches and railroad chronometers since at least the early 20th century, seems to have produced these military pocket watches concurrently with their wartime wristwatches. Both black and white-dial versions are known to collectors, and both largely seem to share the same characteristics: a ~52mm stainless steel case, a 15- or 17-jewel, manually wound movement, a 30-minute counter at 12 o’clock and a running seconds counter at 6 o’clock, and large Arabic numerals (certain versions featured inner 24-hour tracks in red). 

Japanese pilots with chronometers around their necks (Credit: HULTON DEUTSCH/CORBIS VIA GETTY IMAGES)

The black-dialed versions of the watch, in which the Arabic numerals are executed in white in the Breguet style, likely featured radium paint on the hands and indices to aid in night flying and navigation. The cockpit of the Mitsubishi Zero evidently featured a cutout in the dashboard for placement of one of these chronometers, and it’s conceivable that they were removed after each flight and otherwise kept on the airman’s person.


Following the Japanese surrender in August, 1945, the Americans occupied the Japanese mainland and assumed control of its security, preventing the country from raising a standing army. Article 9 of the 1947 Japanese constitution forbade the formation of a military, and Japan became a forward staging area for American forces engaged in Korea in the 1950s. Though self-defense forces were established in 1954 — which over time became the modern Japanese military — relegation of Japanese forces to domestic duties or foreign peacekeeping or humanitarian missions until the 1990s meant there was likely little need for the issue of specialized equipment such as wristwatches.  

Seiko, once again, was at the forefront of Japanese domestic watch production following World War II, and though their wares were utilized by American personnel especially during the Vietnam War, it is less clear if Japanese forces were issued these watches themselves. An examination of the history of issued military watches in post-War Europe and the U.S. reveals an overwhelming number of cases in which watches were largely provided only to troops fulfilling specific, special duties: American Underwater Demolition Teams (UDT) personnel serving in Vietnam, or special operations-capable paratrooper battalions activated in Italy, or German Bundeswehr helicopter pilots, etc. 

Though the Japanese economy boomed in the 1960s, it’s conceivable that a lack of activity beyond domestic peacekeeping duties meant there was little need to develop purpose-specific timepieces for issues to Japanese forces. By the time the JSDF had attained the powerful stature that it enjoys today, the world was well into the “G-Shock era” of military timekeeping, and the issued watch had largely gone the way of the dodo. 

Sources for this article include:

Japan Clock & Watch Association

Japanese Clock Wikipedia

Seiko Watches – Company History

Seiko History – Wikipedia

Europastar Japanese Military Watches

Seiko in WWII – Philippine Watch Club

Watches You Should Know – Seiko Tensoko, Gear Patrol

Phillips Seiko Tensoku

Listing for Seiko Military Pocket Watch – Selling Antiques

Listing for Seiko Military Pocket Watch – Worth Point

History of the Japan Self-Defense Forces – Wikipedia 

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Oren Hartov is the watches editor at Gear Patrol, a contributor to several other publications, and a graduate of the Berklee College of Music. He is a reserve paratrooper in the Israel Defense Forces and enjoys music, history, archaeology, militaria, scuba diving, languages and travel. He is of the opinion that Steely Dan’s “The Royal Scam” may in fact be a better record than “Aja,” but he’s not positive.