Squadron

Squadrons are groupings of aircraft, naval vessels or armoured fighting vehicles.

An air force squadron typically consists of three or four flights,with 12 to 24 aircraft, depending on aircraft type and air force.
An armoured squadron typically consists of four or five troops. In the United States Army, a squadron is the Armor Branch equivalent of a battalion of infantry or artillery; in the British Army, it is the counterpart of an infantry company or an artillery battery.
Naval squadrons are of two types: aviation and surface (or vessels).

A naval vessel squadron is a more ad hoc grouping. The only requirement for a grouping of ships to be a squadron, is that at least two must be capital ships (battleships, battlecruisers, cruisers, or aircraft carriers). In the United States Navy, several ships of a similar type, such as submarines and destroyers, are administered as squadrons.

World War II

Squadrons in WWII:

Imperial Army of Japan

Three Japanese air squadrons were assigned to each air regiment.