The S.O.B. didn't even tell the passengers. He just let them board the ship in order to sacrifice their lives so he could have the glory of leading the U.S. into one of Europe's endless series of incomprehensible wars.
But it's an extreme strectch to say that the sinking of the Lusitania was the excuse to get the US into the war, especially considering that the Lusitania was sunk in May 1915 and the US didn't declare war on Germany until April 1917,
2 years later! The Germans announced the Arabic Pledge in September 1915 after sinking the British liner Arabic, promising not to sink liners. Berlin extended that with the Sussex Pledge in 1916, but insisted that Britain obey international neutrality laws as well. It was following Jutland, when the High Seas Fleet never put to sea again that Germany growing desperate, believed her only chance was to starve Britain into submission, so she announced unrestriced u-boat warfare in January 1917. In February Britain intercepted the Zimmerman Message, which infuriated Wilson, and the American public when it was leaked to the press, and Wilson, who was growing weary of his efforts to negotiate a peace, asked Congress to declare war. While Wilson was a prick, it would be wrong to blame America's entry on any under-handed efforts by him. As a progressive, he genuinely, if not naively, believed for the first two years of the war that America should remain neutral and above the conflicts of Europe. He envisioned taking American progressivism to the world stage, as was later reflected in his 14 points.
2) Use tanks properly, as people LIke General J F C Fuller were suggesting. In mass, with proper support, fuel, and tens of thousands of troops ready to rush through the gap created, and they did create some big gaps, you could have rolled the germans back over a few weeks or months.
Problem was, the first few months the tanks had little success because they proved unreliable, breaking down, not clearing the trenches, or simply getting bogged down. And finally when they begin working the kinks out they found that too often there either weren't enough troops to exploit the break, or the troops had so much trouble moving up that it was easier for the Germans to move reserves up and create new lines. Had armor been introduced a year or so earlier they might have made a bigger difference than they actually did. The British and French broke the German lines a few times, but were simply never able to exploit their successes. I think the blitzkrieg of the 2nd ww showed that they learned from the mistakes of the first ww. Rather than have an inflexible chain of command, where operations are controlled from the rear, you have to have a more flexible command, allowing field commanders along the front, utilizing integrated, coordinated, rapidly moving forces, to exploit weak spots that have been probed. Read Heinz Guderian's
Achtung! Panzer; you should be able to find an English print copy. Like everyone else, he recognized the problems with trench warfare and prepared tactics to prevent the next war becoming bogged down again. He broke German battlefield tactics down into 3 parts: break-in, breakthrough, and exploitation. The first was the intitial breach, the second was achieved when your force reached the point where it had advanced past the static defenses, and the 3rd was doing something positive from that point, which was to advance rapidly enough to disrupt the enemy command system so that resistance fell apart or could be flanked. Guderian had seen the British and French achieve break-in with their armor, but not be able to achieve the other two, mainly because armor couldn't do it alone. You needed to exploit with rapidly moving infantry as well, hence the need not just for infantry, but a mechanized infantry that could advance as rapidly as the armor.