Lerdrit is Thailand's military martial art adapted from Muay Boran, or the traditional arts of Thailand that also spawned the more famous Muay Thai.
Muay Boran is an umbrella term used to describe the different regional fighting arts of Siam that gradually emerged into styles with different footwork, stances and even differing methods of wrapping the knuckles in hemp rope prior to a bout. In times of war glass shards or sharp shells would also be glued into the hemp rope to ensure a bloody result if and when techniques connected.
Royal and upper class interest in Muay Boran led to the creation of a new form:Muay Luang. This latter style was considered appropriate for the Siamese aristocracy but of course such people, and the royal family in particular, needed well-trained warriors to protect them and so these bodyguards also innovated their own style and this spread throughout the armed forces.
This martial art based on traditional fighting systems is used by the Royal Thai Army as its method of unarmed combat. The name means 'extreme power' and it is characterized by the use of palm strikes, kicks, knees and elbows as well as grappling in the clinch.
The wider variety of techniques compared to Muay Thai gives the practitioner more versatility and of course betrays its origins as a battlefield art, a history and combative culture to which it continues to adhere to. These techniques can also be applied to target areas declared illegal in the sport of Thai boxing. The groin, for example, is fair game. Headbutting is also included, but the system is notable for its lack of developed grappling techniques. Generally speaking grappling systems developed to give a warrior options if or when he lost his footing or found himself without a weapon and was forced to take his opponent to the ground to execute some kind of finishing technique. This suggests to me at least that this military form grew essentially from hand to hand fighting techniques rather than those strictly employed by the Siamese warriors.
Despite being related to traditional martial arts, the Thai army today cross-trains in various disciplines in order to continually update and improve their arsenal of techniques.
