Oorah is a battle cry common in the United States Marine Corps since the mid-20th century. It is comparable to hooah in the US Army and hooyah in the US Navy and US Coast Guard. It is most commonly used to respond to a verbal greeting or as an expression of enthusiasm.
Owing to its relatively recent origins, it is less common for Marines who served in the Vietnam War or earlier to be familiar with "Oorah!", but most post-Vietnam Marines and Vietnam War Marines who continued to serve after the war will have learned it throughout their careers. A couple of shortened versions of "Oorah!" can come out as a short, sharp, monosyllabic guttural "Er!" or "Rah!" Another phrase similar to "Oorah" is the bark, also commonly used by Marines, due to the nickname "Devil Dogs" from the Battle of Belleau Wood in World War