IWC developed the first wristwatch designed solely for aviation, the Spezialuhr für Flieger or Special Pilot's Watch, in 1936. But as aviation became militarized at the start of the Second World War, the importance of watches as navigational tools increased. During the war, the British Ministry of Defense called upon manufacturers to design watches that could meet the rigorous standards required for military use. The new standard issued, which the MOD coded 6B/346, required chronometer-grade and anti-magnetic movements. The MoD gave the contract to two manufacturers: Jaeger-LeCoultre and, of course, IWC. Thus, the Mark XI was born.
IWC met the antimagnetic properties by covering the movement with a soft iron cage. Rather than the Caliber 83 movement, the Mark XI was fitted with the Caliber 89, regarded as perhaps the most robust three-hand movements of all time. The Caliber 89 runs at 18,000 bph and features a double barrel, a Breguet hairspring, and a drive for the sweeping seconds hand that IWC patented.
The Ministry of Defense spared no expense in guaranteeing that the watches maintained their accuracy. Each watch was subjected to a 44-day testing period at the Royal Greenwich Observatory, which included 14 days in which the watches were tested in five different positions and at two different temperatures. Once the watches passed these rigorous tests, they had to be returned to the Royal Observatory for testing within a year.
The Mark XI entered military service in 1949 and was decommissioned in 1981. Its size (slightly small by today's standards) belies the sturdiness and dependability of this robust navigating machine. Reliable to the last, it exemplifies the truest notions of a tool watch.
This particular watch is in a true veteran, with signs of wear that speak to the conflicts it's seen. Its case back, a 1951 contract service replacement, was replaced at some point during its life, while its movement serial and dial attest to its early (1947) manufacture, making it one of the first Mark XIs to enter service! Its lovely patina makes this watch very desirable, both for its versatility and as an important horological artifact.
Stainless steel case is approximately 36mm (excluding crown). Caliber 89 Manually-Wound Movement. Circa 1948.
Overall Condition: Case is in good condition overall with normal signs of use and wear consistent with military issued wristwatches. Dial is in excellent condition with crisp printing and no signs of discoloration or hand drag. Luminescent elements of the hour markers and hands have aged to a fine even patina. Unsigned crown. Fixed spring bars have been replaced and re-welded at some point, likely when the watch was decommissioned. Case back is stamped "6B/340 501/51."
Includes two 18mm nylon straps from Crown & Buckle