Why did the German sinking of the Lusitania make Americans angry

There were many Americans on the ship

The Lusitania, a British liner, was sunk by a German U-boat without any warning, 1,195 people were killed. There were 123 Americans on board. The fact fueled anti-German feelings in the United States, the public was outraged. The German embassy had published ads warning that British ships could be the target of German vessels because of the war. Nevertheless, it was assumed in the US that passengers would be allowed to get onto lifeboats before an attack.