The rank traces its origins to the Middle Ages where the title of Lieutenant General was held by the second in command on the battlefield, normally subordinate to a Captain General.
In most nations, a Lieutenant General ranks immediately below a General and above a Major General.
General of the Air Force, however, has never been worn by an officer of the modern Air Force on active duty.
The oddity in precedence, where a Lieutenant General outranks a Major General whereas a Major would normally outrank a Lieutenant, is caused by the rank of Major General previously having been known as Sergeant Major General, which was in turn subordinate to Lieutenant General.
Major General or Major-General is a military rank used in many countries.
While historically an army rank, General is also used in most air forces, although those based on the British Royal Air Force use Air Marshal instead, with Air Officer being the generic title.
In most navies of the world, the equivalent rank is Admiral and the generic term is Flag Officer; however a noteworthy historical exception was the Cromwellian naval rank General at sea.