The Navy first authorized garrison caps as optional components of the khaki and green working uniforms worn by Naval Aviators before the start of World War II; these of course included Officers, but Warrant Officers and CPOs could also become aviators through the Navy’s Naval Aviation Pilot program (the last non-commissioned Navy pilot retired in 1981). In 1943, the Navy expanded wear of the garrison cap to include any personnel who wore the peaked cap, and also approved wear of the garrison cap with standard blue and white service uniforms as well as all color variations of the working uniform (the cap did remain an optional item for both enlisted Sailors and Officers throughout this period).
Garrison caps offered many of the same types of benefits as the white service hat, or “Dixie cup”—they were inexpensive, required few materials to manufacture, were easily stowed and took up negligible space, and were easy maintain—attributes not shared by the more delicate peaked cap.
Today, the khaki garrison cap is worn by senior enlisted Sailors (E-7 and above), Warrant Officers (W-2 to W-5), and Officers. Chief Petty Officers wear a miniature CPO cap device on the wearer’s left of the cap; Officers and Warrant Officers wear their respective cap devices on the left and their rank insignia on the right.