The Royal Military College of Canada dress uniform includes such a hat, and similar caps were standard issue for the Victorian era British Army.
Another cap called a kilmarnock is a modern version of the traditional headdress worn by members of virtually all Gurkha regiments.
[2] The modern woman's pillbox hat was created by milliners in the 1930s, and gained popularity due to its elegant simplicity.
Pillbox hats were made out of wool, velvet, organdy, mink, lynx or fox fur, and leopard skin, among many other materials.
[3] Actress Natalie Portman wore a pillbox hat to play Kennedy in the 2016 biographical drama Jackie.