Originally posted by GScholz
Modern nuclear submarines are considered ships, however in WWII they were classified as boats. A WWII submarine is no more a warship than a PT boat. The WWII submarines did not operate with the rest of the fleet like ships of the line, but rather were a separate service in most if not all navies.
Considering that German subs nearly brought Britain and the US's war effort to it's knees, and the US subs crippled the Japanese war effort as well, with several hundred million tons sunk, it is fair to say that a submarine is indeed a warship.
Websters online says:
http://dictionary.reference.com/search?q=warship2 entries found for warship.
war·ship ( P ) Pronunciation Key (wôrshp)
n.
A combat ship. Also called man-of-war.
n : a government ship that is available for waging war [syn: war vessel, combat ship]
Source: WordNet ® 1.6, © 1997 Princeton University
Now IMHO that pretty much says that a sub is a warship in my book. But if you choose to split hairs, and the sub a boat (US Navy budgeting calls subs ships) then lets look up the definition of a ship:
http://dictionary.reference.com/search?q=ship"A vessel of considerable size for deep-water navigation."
considerable size would seem to include a 311 foot submarine displacing 1870 tons.
then I think we can safely call a sub a ship even if it is different tradition to call it a "boat" and it also concludes that a ship is a vessel. Well, to conincide websters says a sub is a vessel too:
http://dictionary.reference.com/search?q=submarineLastly, GScholz is wrong to state that subs never worked in concert witht the fleet at all. US Subs worked on many occasions with fleet battle groups. Notably in fleet air rescue, as well as outlying radar pickets. So, a sub is just as much a ship as is the rest of the fleet.