Say “MilSub” to a watch collector and you might just see them go weak at the knees—or momentarily lost for words. The Rolex Military Submariner, or “MilSub,” was produced in the 1970s in extremely small quantities (just over 1,000 pieces), of which only a few hundred are believed to survive today. It’s no surprise these watches are considered true grails—often commanding between €200k and €500k depending on condition and provenance. But what’s the story behind these rare Submariners? Although produced in the 1970s, the MilSub’s origins trace back to World War II and the rise of underwater combat operations. The Italians were early pioneers in this field, using Panerai watches—interestingly manufactured by Rolex at the time. Great Britain soon followed, commissioning purpose-built watches capable of withstanding prolonged underwater missions. After the war, this evolved into ongoing diving operations within the British Ministry of Defence (MoD), which required reliable, purpose-built wristwatches. By 1957, the MoD approached Rolex with a clear set of specifications. Rolex responded by adapting its Submariner with fixed spring bars, a larger bezel for operation with gloves, and dials using tritium lume (marked by the encircled “T”) instead of the more hazardous radium. For a brief period, the MoD turned to Omega, commissioning military versions of the Seamaster 300. However, in the early 1970s, they returned to Rolex—likely due to the superior water resistance offered by Rolex’s screw-down crown system. One requirement carried over from the Omega designs was the use of “sword hands,” providing greater lume surface and improved underwater legibility. The Submariner reference 5513 was subsequently modified to meet these specifications. Changes included fixed bars, a fully graduated 60-minute bezel insert, a matte dial, and the distinctive sword hands. Over the course of the 1970s, these watches underwent subtle evolutions. Early examples were marked “5513” between the lugs, followed by versions bearing both “5513” and “5517,” with the final series marked solely “5517.” These watches were issued primarily to two branches of the British military: Army (W10 designation)Case backs were engraved with: W10 (MoD code for the Army) 6645 (NATO code for time-measuring instruments) 99 (NATO country code for the UK) 923-7697 (NATO code for divers’ watches) Broad Arrow marking Issue number and year Royal Navy (0552 designation)Case backs were engraved with: 0552 (Royal Navy service code) 923-7697 (NATO code for divers’ watches) Broad Arrow marking Issue number and year Inside the case back of a correct MilSub, one would typically find engravings indicating the model reference, the date of manufacture for the case or case back, and—depending on the batch—the serial number matching the case. The example offered here is a reference 5513 that has, over time, lost some of its original military-spec characteristics. The dial, hands, and bezel insert were replaced during a Rolex service, giving the watch a more “civilian” Submariner appearance at first glance. Additionally, the external military engravings on the case back have been polished away. However, the fixed bars remain intact, and the full serial number is still present inside the case back. A noteworthy historical detail: Henry Hudson, later General Manager of Rolex UK, led the department responsible for delivering military-spec Submariners to the British forces in the 1970s. He preserved detailed records of each issued watch, including serial numbers, case-back engravings, and assigned units or dockyards. The watch at hand has been “civilised”—with the external case-back engravings removed and its original military dial and bezel insert replaced. Today, it is fitted with a later tritium service dial with white gold surrounds, matching tritium-filled Mercedes hands, and a civilian bezel insert. This “stealth” MilSub is paired with one of our single-pass straps—just as a proper military Submariner should be worn. It is accompanied by a Rolex service card dated May 2013 and has been fully serviced again by our watchmaker. For those seeking the essence of a true military tool watch—without having to sell the house—this represents a compelling opportunity, priced accordingly. Specifications: Rolex Submariner Reference 5513 Serial 392xxxx dating to 1975 Fixed bars Serial of the watch repeated inside case back Later, service dial and hands with white gold surroundings, later insert non MOD Rolex service papers from 2013 Fully serviced by our watchmaker 1 year mechanical warranty Free worldwide Fedex Priority shipping