The wristwatch, with a history going back to the 16th century, is certainly a notable invention.
The first modern wristwatch was commissioned to Abraham-Louis Breguet, by Maria Carolina of Austria, Queen of Naples and Sicily, on June 8th, 1810. Maria Carolina was already one of Breguet’s best clients and this time ordered “a grande complication carriage watch” for the price of 2,000 francs, and “a repeater watch for bracelet” for the price of 5,000 francs. Breguet took two years to develop the latter piece, which was a thin oval repeater, held by a wristlet of hair and gold thread. He presented the watch to the Queen in 1812, therefore creating and commercializing the world’s first wristwatch.
Wristwatches continued to be manufactured throughout the 19th century, although largely for women until they began to be used by the military as part of their equipment. Soldiers could no longer go into their pockets to check the time as warfare was now conducted primarily using firearms and artillery, making it too dangerous. As an example, Constant Girard of Girard-Perregaux produced an edition of 2,000 pieces in 1880 for German navy officers.
The development of wristwatches eventually blossomed into what were known as 'wristlets' in the early 20th century. Wristlets would eventually be replaced by the concept of 'tool watches', which became prominent post-WWI as militaries around the world had equipped their soldiers with timepieces (see the trench watches of WWI). It was towards the Great Depression that wristwatches started to definitively be seen as unisex, beginning the rapid commercialization that has continued to this day.