As with many fashion trends in times gone by, the wristwatch was originally made fashionable by royalty — especially Queen Elizabeth I who was given one in the latter 1500s. The first widely worn watches were designed exclusively for girls and called wristlets.
Military watches, as their name implies, were developed for the armed forces. The 1st armed forces watches were naval pieces, chronometers that worked okay for their purposes, but as other branches of the army – aviation particularly – made major technical advances round the time of the second World War, correct measurement of the seconds became crucial.