United Kingdom
British officer’s stiff service-dress cap (WWI)
Here is a terrific example of a typical stiff officer’s service dress cap—also called an “SD” cap—from about 1914. Apart from the fact that the overall quality is rather higher than the stiff cap for enlisted personnel, the only giveaway that this is actually an officer’s cap is the thick leather chinstrap with leather sliders. Enlisted men’s caps have metal “furniture”—which is the British army’s term for hat hardware such as buckles. The badge is for the Manchester Regiment.

Not surprisingly, the cap bears the mark of a local uniform maker in Manchester.