Torpedoes
Torpedoes were used by submarines. The Germans used torpedoes to blow up ships carrying supplies from America to Britain.
The Germans torpedoed the passenger liner Lusitania on May 1st 1915 which sank with a loss of 1,195 lives. Americans were outraged and joined the war in 1917 on the side of the allies.
The term torpedo was originally employed for a variety of devices, most of which would today be called mines. From about 1900, "torpedo" has been used strictly to designate an underwater self-propelled missle
While the battleship had evolved primarily around engagements between armoured ships with large-caliber guns, the torpedo allowed torpedo boatsand other lighter surface ships,and later,the aircraft to destroy large armoured ships without the use of large guns, though sometimes at the risk of being hit by longer-range shellfire.