The two most import catalysts for the development of aviation watches were early aviation record attempts and war. World War I finds watch development between the pocket watch and the new wristlets with the British issuing pilots pocket watches. British Mark IV.A and Mark V pocket watches are an example of WW1 military aviation.World War I conjures childhood images of bi-planes fitted with a machine gun to fire through the propeller, the Red Baron's plane emerging triumphant from a dogfight, and the endless lines of trenches on the ground below. Add the romanticism of aviation to the romanticism of war, and you have an iconic, if mistakenly idealized, pairing. War's demand for precise navigation or coordinated attack meant that the world grasped the importance of horology. When “balloon busting” or taking out observation balloons, British pilots flew with the pocket watch Mark IV.A (1914) and Mark V (1916).Doxa Mark V (source: Military Watch Forum)Case back markings, unique to country, branch of service or intended use, are a distinguishing characteristic of vintage military watches. Great Britain's characteristic mark was the broad arrow. For the collector, case back markings are key identifiers and an added authenticity safeguard. These markings meant that the watches were official military equipment, procured through contracts and mass-produced for combat pilots. Ad - Scroll to continue with article On April 13, 1912, the British Army's Royal Flying Corps (RFC) was formed to develop a military and naval wing. Just prior to the war, given the unique needs of the fleet, the naval wing severed with the RFC to form the Royal Naval Air Service (RNAS). In 1918, these two separate aviation branches merged again to form the Royal Air Force (RAF) who continued to use the Mark watches. The RFC aviation issue watches had an underscored capital A with a broad arrow pointing upward underneath it. Repairs to the watch meant an additional caseback stamp marking the repair status. One look at the caseback, and the markings tell you, British issue.Omega Mark V (source: Military Watch Forum)Mark IV.A (1914) and Mark V (1916) pocket watches were standard issue. The RFC and RNAS had near identical watches, but the RNAS watches were predominately the eight-day variety and the RFC, the 30-hour. Once inside the aircraft, these watches became chronometric instruments, which the pilot fit into the instrument panel. As a result, the Mark IV.A and Mark V had long shank winding stems to extend beyond their instrument panel housing for mid-flight winding, earning the nickname, cockpit watch. German pilots, on the other hand, wore inverted watches suspended from a fob on their flight suits. Zeppelin pilots had rapid access to time, and the hanging, inverted dial was right side up when held. These adaptive measures were precursors to the pilot watch worn on the wrist.Smith Mark IV.A – 8 day (IHC 185)?Numerous manufacturers supplied Mark watches with unsigned movements; retailers like H. Williamson Ltd. Of London or Birch & Gaydon Ltd. of London distributed these anonymous watches. The Smith watch company was a leading provider of Mark IV.A watches and bragged, Because of its splendid time keeping and unfailing accuracy this instrument has gained the reputation of being the most successful watch yet designed for constant use on Aircraft. The four known manufacturers of Mark V watches were Zenith, Omega, Doxa and Electa.Williamson Ltd. Mark IV.A 8-Days?Mark watches had various configurations. Night flying required the issue of luminous editions so that pilots could monitor fuel consumption and navigate in the dark. The eight-day Mark V model was ideal for longer flights. The rigors of flight demanded thermal compensation, accuracy and shock-resistance. Form follows function, and the aviator's tool was shaped by its intended use, and nowhere was that use more crucial than in combat. Forged in the fires of warfare, the pilot watch's functionality expanded and would continue to expand.British Sopwith SE5 WW1 bi-plane?War is serious business. Its existence is evidence of human failure, and war's sometimes unavoidable necessity requires better than the best effort possible. The exigencies of war called the watchmaking industry to respond with their best effort, making war a catalyst for horological advance. WW1 was the beginning of an appreciation of the watch as essential military equipment. Yet after the horrors of World War I ravaged Europe, Omega issued watches in France which were embossed with the dove of peace. Without celebrating violence, we can celebrate the technological feats achieved amidst appalling circumstances. Mark IV.A and Mark V watches exemplify WWI horological achievement.Resource: A Concise Guide to Military Timepieces: 1880-1990 by Z.M. WesolowskiCheck out History of the Pilot Watch Part I, II, IV and V by clicking on the images below.