A patrol cap, also known as a field cap, is a soft kepi with a stiff, rounded visor, and flat top, somewhat similar to a baseball cap, worn by the military personnel of some countries in the field when a combat helmet is not required.
The M1951 Field Cap, introduced with the M1951 Uniform, was a derivative of the M1943 Field Cap, part of the M1943 Uniform. The M1951 cap was worn in the Korean War, where it became known as the "patrol cap" by the US Army Rangers there. It was constructed of wind-resistant olive drab cotton poplin, and had a flannel wool panel that folded down to cover the ears and the back of the head. It was soft enough to be worn underneath an M-1 helmet. After the Korean War, the cap was replaced by the Ridgeway Cap, a stiffened version of the M1951. The hat became famous outside America by being worn by Fidel Castro. The patrol cap was replaced altogether in 1962 with a baseball-like "Cap, Field (Hot Weather)" and during the Vietnam War by the boonie hat.
On June 14, 2011, the M1951/ACU soft patrol cap became once again the primary headgear for all Soldiers as the duty uniform headgear after a 10-year hiatus in favor of the beret, according to Army Directive 2011-11.
In 1981, following the introduction of the M81 Battle Dress Uniform, the patrol cap was reintroduced. The patrol cap continues to be worn with the Army Combat Uniform, introduced in 2004. The materials are 50% cotton, 50% nylon blend. It has been available in different variants and patterns, such as hot weather models which have eliminated the ear flaps. Patterns have included M81 Woodland, Six color desert camouflage, Three color desert camouflage, and the Universal Camouflage Pattern. The ACU patrol cap features a velcro-backed patch on the back with the soldier's name printed on it and a small internal pocket, the soldier's rank insignia is pinned on the front, as seen in the image below. The patrol cap also comes in a pixelized version of the Tigerstripe camouflage pattern, worn with the United States Air Force's Airman Battle Uniform. In late 2010, the US Army began issuing the MultiCam pattern for use in Afghanistan. It is now being introduced to patrol caps and the ACU to provide the best camouflage possible.