Final answer:
The ship that was sunk by German U-boats leading to 128 US citizen deaths and war demand was the RMS Lusitania. It was torpedoed off the coast of Ireland while carrying ammunition, culminating in public outcry and pressure on President Wilson to declare war.
Step-by-step explanation:
The American ship that was sunk by German U-boats, leading to the death of 128 US citizens and stirring demands for war, was the RMS Lusitania. It was a passenger liner sailing from New York City to Liverpool in May 1915. Carrying four million rounds of ammunition in its cargo hold, the ship became a target of German submarines due to the German high command's policy of unrestricted warfare. Subsequently, off the coast of Ireland, the RMS Lusitania was torpedoed by a German submarine and sunk in about twenty minutes.
This incident, together with the sinking of other American ships, built pressure on President Wilson to declare war. However, despite the public outcry, Wilson maintained neutrality in Europe's war. Nevertheless, the unrestricted submarine warfare announced by Germany in January 1917 made any ship in a war zone a target, essentially pushing the United States closer to the war.
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