Employment of Sea Power: WWII Atlantic & Mediterranean Theaters 1956 US Navy Training Film MN-8512A

more at http://quickfound.net/

Originally a public domain film from the US Navy, slightly cropped to remove uneven edges, with the aspect ratio corrected, and one-pass brightness-contrast-color correction & mild video noise reduction applied.

The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).

https://en.wikipedia.org/wiki/Command_of_the_sea

Wikipedia license: http://creativecommons.org/licenses/by-sa/3.0/

Command of the sea (also called control of the sea or sea control) is a naval military concept regarding the strength of a particular navy to a specific naval area it controlled. A navy has command of the sea when it is so strong that its rivals cannot attack it directly. This dominance may apply to its surrounding waters (i.e., the littoral) or may extend far into the oceans, meaning the country has a blue-water navy. It is the naval equivalent of air supremacy.

With command of the sea, a country (or alliance) can ensure that its own military and merchant ships can move around at will, while its rivals are forced either to stay in port or to try to evade it. It also enables free use of amphibious operations that can expand ground-based strategic options. Most famously, the British Royal Navy held command of the sea for long periods from the 18th to the early 20th century, allowing Britain and its allies to trade and to move troops and supplies easily in wartime while its enemies could not (the importance of which is reflected in the famous British patriotic song, "Rule, Britannia!," which contains the exhortation, "Rule Britannia! Britannia rule the waves," even if this was not the poem's original subject). For example, Britain was able to blockade France during the Napoleonic Wars, the United States during the War of 1812, and Germany during World War I. In the post-World War II period, the United States has had command of the sea.

Few navies can operate as blue-water navies, but "many States are converting green-water navies to blue-water navies and this will increase military use of foreign Exclusive Economic Zones [littoral zone to 200 nautical miles (370 km)] with possible repercussions for the EEZ regime."...

During the age of sail, there were two primary counter measures to another power holding control of the sea: smuggling, and privateering. Smuggling helped to ensure that a country could continue trading (and obtaining food and other vital supplies) even when under blockade, while privateering allowed the weaker power to disrupt the stronger power's trade. As these measures, which are examples of asymmetric warfare, came from non-governmental and sometimes criminal organizations, they fell into disfavor with stronger governments. An annex to the Treaty of Paris (1856) banned privateering. That treaty was an oddity in that it was ratified by relatively few countries, but quickly became the de facto law of the sea.

Historic command of the sea in the era of steam

A more modern countermeasure, similar to privateering, was the use of submarine warfare by Germany during World War I and World War II to attack allied merchant shipping primarily in the Atlantic Ocean, Mediterranean Sea, and Baltic Sea.

Historic command of the sea in the era of naval aviation

During World War II, aircraft also became an effective countermeasure to command of the sea, since ships could not defend themselves well against air attack. The Battle of Britain was largely an attempt by Germany to eliminate the Royal Air Force, so that it would not be able to defend the Royal Navy from air attack and even to allow a maritime invasion of Great Britain proper...

Advanced navies, with access to surveillance satellites and large-scale submarine detection systems, can rarely be surprised at sea, but cannot be everywhere. Individual ships of advanced navies can be vulnerable at sea (e.g., the USS Stark hit by an aircraft-delivered anti-ship missile while patrolling the Persian Gulf) or in port (e.g., by the suicide attack on the USS Cole.)

"Blue-water" (high seas) naval capability  means that a fleet is able to operate on the "high seas." While traditionally a distinction was made between the coastal brown-water navy (operating in the littoral zone to 200 nautical miles (370 km) and a seagoing blue-water navy, a new term, "green-water navy," has been created by the U.S. Navy, which refers to the coastal submarines and fast attack boats of many nations, the larger littoral combat corvettes and similar vessels of a substantial number of powers, and amphibious vessels ranging from elderly LSTs to complex S/VTOL carriers and other specialized ships.

The term brown-water navy appears to have been reduced, in U.S. Navy parlance, to a riverine force...