Early Revolver Speed Loader - The Prideaux Speedloader (1893)
The Prideaux speed loader was one of several early such devices patented and manufactured as early as 1893, but neither it nor any competitor saw much demand until the outbreak of World War One. At that point, a substantial number were purchased privately by individual officers for use in the trenches – enough that they came to the attention of the British military administration. In October of 1918 the Prideaux specifically was formally adopted by the British military, although none were procured until after the war ended – all surviving military examples show 1919 dates.
This is one of the exemplars of Forgotten Weapons. It very much so is a historical oddity, with more complexity than we'd use today, that speaks to the environment of it's time.
The problem of getting back to a fighting state once your gun has run dry has been a problem for quite some time. This historical example offered a solution. The best? perhaps not. The available? Most definitely.