Laying the ground work for WWII
Longstreet, in his own words, wanted “to throw ourselves between the enemy and Washington and force the enemy to attack us.” Then the Confederate cavalry could capture unguarded Washington and the war was over...Well it did not happen that way.
If Wilson had taken Secretary of State William Jennings Bryan's advice to prevent the Allies and the Germans from buying war materiel from the United States. Then, without the American weaponry, munitions and loans, the Allies would have been forced to abandon their goal of "knockout blow". The war might well have ended in 1915 or 1916 as the conflict would have become a trench war stalemate, leading to a negotiated peace.
Wilson, the dolt, refused the advice and the war dragged on. Next, he very much wanted a seat at the negotiations. In 1917 the Germans, because of America's large arms sales to Great Britain, informed their ambassador to Washington that they did not want Wilson to play any part in peace negotiations. Lloyd George convinced Wilson that unless America intervened with troops, the president would have no place at the peace table. The US enters the war in 1917. Once again, the man in charge makes the wrong decision.
German aims before the war began were realistic. Berlin sought an acknowledgment that Germany was Continental Europe's dominant power. They wanted an independent Poland and nationhood for the Baltic states to keep Russia away from their eastern border. Also they wanted a free trade zone in which German goods could circulate without high tariffs in France, Italy, Scandinavia and Austria-Hungary*. But the British Tories did not want such a commercial rival and in 1914 opted for war. The French, still smarting from their defeat in 1870, wanted revenge. So when the fuse was lit with the murder of Archduke Franz Ferdinand, they all jumped into the abyss.
* What they wanted is not so different from the role Germany plays in the European Union now.