HMS Dreadnought, launched in 1906. The ship that changed modern warfare for Battleship era.
The Dreadnought, perhaps needs no introductions. She was ship that put capital "B" in name Battleship. Her revolutionary design, changed many things, all ships built prior to her became pre-Dreadnoughts.
The ship itself perhaps less active, perhaps because her being the prototype of new generation of warships, the Dreadnought didn't do whole lot in her career. However, from 1906 to 1911, she was most powerful warship afloat. She was mainly used a flagship for entire fleet, to respective squadrons of follow-on designs.
During World War I, she had one significant action during the war. She is only Battleship to ever sink submarine, purposely. You would think "How did they do that?" You do it the old fashion way, you ram it! After one her squadron mates were fired on (HMS Neptune), she purposely went after the submarine U-29 had broken the surface. She managed cut the submarine in two, while nearly colliding with another British ship in the process.
