Instinctive behavior occurs when an animal has a particular internal state while it is in the presence of a specific external stimulation called a releaser or a sign stimulus.
How many ships did the U-boats sink? During the war the U-boats sank about 2,779 ships for a total of 14.1 million tons GRT. This figure is roughly 70% of all allied shipping losses in all theatres of the war and to all hostile action. The most successful year was 1942 when over 6 million tons of shipping were sunk in the Atlantic.
Sinking ships without warning. German's sunk the Bristish passenger ship Lusitania May 1915. 1200 killed included 130 Americans. Wilson demanded reparations and apology. Bryan instructed to send memo to Germany, hesitant, but did. Germans said Lusitania was armed (false) and carrying military cargo (true, British was using civilians to shield war cargo). Bryan refused to write 2nd note and resigned as Sec of State.