when were submarines first used in world war 1
U-boat On 5 September 1914, HMS Pathfinder was sunk by SM U-21, the first ship to have been sunk by a submarine using a self-propelled torpedo. On 22 September, U-9 sank the obsolete British warships HMS Aboukir, HMS Cressy and HMS Hogue (the "Live Bait Squadron") in a single hour.
USS Blueback (SS-581) Blueback was decommissioned on 1 October 1990 and laid up in the Pacific Reserve Fleet in Bremerton, Washington. She was struck from the Naval Vessel Register on 30 October 1990. With her removal from service, the last warship that was a diesel-electric submarine of the United States Navy had left the fleet, leaving the research submarine USS Dolphin (AGSS-555) as the last diesel submarine of the US fleet.