Berets of the United States Army
U.S. Army Special Forces wear the green beret because of their link to the British Commandos of World War II. The first Ranger unit, commonly known as Darby's Rangers, was formed in Northern Ireland during the summer of 1942. On completion of training at the Commando Training Depot at Achnacarry Castle in Scotland, those Rangers had the right to wear the British Commando green beret, but it was not part of the regulation uniform at the time and was disallowed by the U.S. Army. 
The 10th Special Forces Group (Airborne) had many veterans of World War II and Korea in its ranks when it was formed in 1952. Members of the 10th SFG began to unofficially wear a variety of berets while training, some favoring the red or maroon airborne beret, the black beret, or the green commando beret. In 1953, a beret whose design was based on that of the Canadian Army pattern, and which was rifle-green in color, was chosen for wear by Special Forces units.
Military beret
With the exception of the Naval Commandos (Commandos Marine) and the Naval Infantry (Fusiliers Marins), whose berets are worn pulled to the right, all other French military berets (army, air force and Gendarmerie) are pulled to the left with the badge worn over the right eye or temple.
Gendarmerie personnel serving with the European Gendarmerie Force (EUROGENDFOR) – an EU crisis response and intervention force – wear the standard EUROGENDFOR royal blue beret and badge when so assigned.
Dark Green - Naval Commandos - (Badge on the left)