The present watch is a prototype of the first Panerai chronograph, the "Mare Nostrum", originally designed to be used by deck officers of the Italian Navy. Only very few of these watches were made in 1943 but due to the turmoil during the war, the model never went into production but remained at the prototype stage. It was not until 50 years later that Officine Panerai reproduced the Mare Nostrum chronograph, the first examples made in 1993 in a limited series.
The 1943 prototype is illustrated in La Panerai di Firenze - 150 anni di storia by Dino Zei, p. 67.
Officine Panerai was founded in 1860 by Giovanni Panerai (1825-1897) who opened the first watchmaker's shop in Florence on the Ponte alle Grazie and became a retailer of Switzerland's most prestigious watch manufacturers. At the turn of the century, the shop moved to Piazza San Giovanni where it is still today and the designation "Orologeria Svizzera" was added. In the following years Giovanni Panerai's grandson Guido Panerai (1873-1934) expanded the business by specializing in the production of high precision optical and mechanical instruments, thus becoming the official supplier to the Royal Italian Navy.
As of 1910, the innovative Guido began experimenting with luminous materials and developed a system rendering instrument dials, sighting and telescopic devices luminous. His invention, later known as "Radiomir" and patented, consisted of a mix of sulphide and radium bromide to achieve luminescence. During both World Wars, the Royal Italian Navy used various Panerai precision instruments including timing mechanisms, depth gauges and mechanical calculators to launch torpedoes from high speed motor torpedo boats "M.A.S" or "Motorbarca Armata SVAN", manufactured by the Societa Veneziana Automobili Navali or SVAN. These "human torpedoes" were electrically propelled torpedoes with two crewmen equipped with diving suits riding astride. The torpedo was steered at slow speed to the enemy ship, the detachable warhead then used as a limpet mine before riding away.
When Guido passed away in 1934, his children Giuseppe and Maria continued and further developed their father's business. Maria took over the day-to-day running of the Orologeria Svizzera shop while Giuseppe devoted his entire time to the improvement of underwater instruments, torches, wrist compasses and wrist depth gauges for the Royal Italian Navy.
Following disappointing tests carried out on watches available at that time, the Royal Italian Navy approached Panerai with the request of designing a watch resistant to extreme conditions while at the same time keeping exact time. The prototype which Panerai submitted to the First Submarine Group Command was called "Radiomir" and passed all tests successfully; as of 1938, small series of "Radiomir" watches for the Italian Navy were produced. The models were fitted with hand-wound movements supplied by Rolex, the dials consisted of two discs, a lower one coated with "Radiomir" luminous substance visible through the cut out numerals in the black upper disc, enabling the easy reading in the dark or under water. The large cushion-shaped cases had a diameter of 47 mm, wire lugs and a screw-down crown.
From the launch of the "Radiomir" until to date, Panerai designed the crown protecting device, allowing the watches to descend to a depth of 200 metres, a remarkable achievement for the time. It was also granted patent for "Luminor", the luminous substance based on tritium, which replaced the previous "Radiomir" mix, and from which the names of the two models are derived.
The firm supplied small series of diver's watches to several Mediterranean Navies including a large Radiomir watch made upon request of the Egyptian Navy, fitted with an Angelus movement with 8-day power reserve and 5-minute intervals to calculate immersion times.
Today more than ever Panerai watches with their distinctive look enjoy an enormous popularity amongst collectors.