A flagship is a vessel used by the commanding officer of a group of naval ships, reflecting the custom of its commander, characteristically a flag officer, flying a distinguishing flag. Used more loosely, it is the lead ship in a fleet of vessels, typically the first, largest, fastest, most heavily armed, or best known.
Over the years, the term "flagship" has been borrowed in metaphorical form by industries such as broadcasting, automobiles, cell phones, education, national airlines, breweries and retailing to refer to their highest profile or most expensive products and outlets.
In common naval use, the term ''flagship'' is fundamentally a temporary designation; the flagship is wherever the admiral's flag is being flown. However, admirals have always needed additional facilities; a meeting room large enough to hold all the captains of the fleet, and a place for the admiral's staff to make plans and draw up orders.
In the age of sailing ships, the flagship was typically a first-rate; the aft of one of the three decks would become the admiral's quarters and staff offices. This can be seen today on HMS ''Victory'', the flagship of Admiral Nelson at the Battle of Trafalgar, now at Portsmouth, England. HMS ''Victory'' still serves the Royal Navy today as the ceremonial flagship of the First Sea Lord,〔(HMS ''Victory'' – home page )〕 making her the oldest commissioned warship in service. The USS ''Constitution'', which also served in her day as flagship of the United States Navy, is 34 years younger, but is the oldest commissioned warship still afloat.
In the 20th century, ships became large enough that most types could accommodate a commander and staff, and during World War II admirals would often prefer a faster ship over the largest one. Some larger ships may have a separate flag bridge for use by the admiral and his staff while the captain commanded from the main navigation bridge. Because its primary function is to coordinate a fleet, a flagship is not necessarily more heavily armed or fortified than other ships.
Modern flagships are designed primarily for command and control rather than for fighting, and are also known as command ships.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』