Military organization
At the top of the ladder, what other nations would call an army group, the Red Army called a front. By contrast, during the same period the German Wehrmacht army groups, particularly on the Eastern Front, such as Army Group Centre significantly exceeded the above numbers, and were more cognate with the Soviet Strategic Directions.

Navy: Naval organization at the flotilla level and higher is less commonly abided by, as ships operate in smaller or larger groups in various situations that may change at a moment's notice.  However, there is some common terminology used throughout navies to communicate the general concept of how many vessels might be in a unit.
Navies are generally organized into groups for a specific purpose, usually strategic, and these organizational groupings appear and disappear frequently based on the conditions and demands placed upon a navy.  This contrasts with army organization where units remain static, with the same men and equipment, over long periods of time.

The five-star ranks of admiral of the fleet and fleet admiral have largely been out of regular use since the 1990s, with the exception of ceremonial or honorary appointments. Currently, all major navies (blue-water and green-water navies) are commanded by an admiral of either four-star rank or three-star rank depending on relative size. Smaller naval forces, such as the Royal New Zealand Navy, or those navies that are effectively coast guards, are commanded by a rear-admiral (two-star rank), commodore (one-star rank) or even a captain.
Aircraft carriers are typically commanded by a captain. Submarines and destroyers are typically commanded by a captain or commander.  Some destroyers, particularly smaller destroyers such as frigates (formerly known as destroyer escorts) are usually commanded by officers with the rank of commander. Corvettes, the smallest class of warship, are commanded by officers with the rank of commander or lieutenant-commander. Auxiliary ships, including gunboats, minesweepers, patrol boats, military riverine craft, tenders and torpedo boats are usually commanded by lieutenants, sub-lieutenants or warrant officers.  Usually, the smaller the vessel, the lower the rank of the ship's commander.  For example, patrol boats are often commanded by ensigns, while frigates are rarely commanded by an officer below the rank of commander.
Historically, navies were far more rigid in structure.  Ships were collected in divisions, which in turn were collected in numbered squadrons, which comprised a numbered fleet.  Permission for a vessel to leave one unit and join another would have to be approved on paper.
The modern U.S. Navy is primarily based on a number of standard groupings of vessels, including the carrier strike group and the expeditionary strike group.
Additionally, naval organization continues aboard a single ship. The complement forms three or four departments (such as tactical and engineering), each of which has a number of divisions, followed by work centers.

Air force: The organizational structures of air forces vary between nations: some air forces (such as the United States Air Force and the Royal Air Force) are divided into commands, groups and squadrons; others (such as the Soviet Air Force) have an Army-style organizational structure.  The modern Royal Canadian Air Force uses Air division as the formation between wings and the entire air command.  Like the RAF, Canadian wings consist of squadrons.

Task force: A task force is a unit or formation created as a temporary grouping for a specific operational purpose.  Aside from administrative hierarchical forms of organization that have evolved since the early 17th century in Europe, fighting forces have been grouped for specific operational purposes into mission-related organizations such as the German Kampfgruppe or the U.S. Combat Team (Army) and Task Force (Navy) during the Second World War, or the Soviet Operational manoeuvre group during the Cold War. In the British and Commonwealth armies the battlegroup became the usual grouping of companies during the Second World War and the Cold War.
Within NATO, a Joint Task Force (JTF) would be such a temporary grouping that includes elements from more than one armed service, a Combined Task Force (CTF) would be such a temporary grouping that includes elements from more than one nation, and a Combined Joint Task Force (CJTF) would be such a temporary grouping that includes elements of more than one armed service and more than one nation.

See also: Command and control
Military administration

Explanatory notes: 

== References ==