Plan developed at the turn of the century by the German High Command to invade America while Teddy Roosevelt was President and force a treaty.
Kaiser Wilhelm II of Germany really hated America, the same way that Al-Qaeda hates us today. And like Al-Qaeda, he sought to attack the very thing that made America great: Capitalism.
Germany wanted to have an overseas empire, and felt that the United States was standing in its way. They wanted to force America to curtail its power in the Pacific, allowing for German dominance. The Kaiser felt this was the only way he could "put America in its place."
The plan drawn up by the German High Command was to take 60 ships of the German Navy along with 100,000 men and size the City of Boston while bombarding Manhattan. The idea being that an attack on America's financial heart would cause the country to loose its collective shit (sound familiar, yet?) and demand that President Roosevelt make peace with Germany. Apparently, the Germans were unaware of how Roosevelt handles threats, and bullies, and war ... and life for that matter.
And just what German would be crazy enough to threaten this man in a negotiation? He's already beating you up with his eyes!!
Teddy Roosevelt happened. Being the former Assistant Secretary of the Navy before resigning to go off and kill some Spaniards, TR realized that America was vulnerable at its coastlines and decided during his first term to build up and modernize the U.S. Navy. In 1907, during his second term, TR decided to show off his "big stick" by sending the Navy's battle fleet, now known as the Great White Fleet on a trip around the world what the U.S. was capable of.
Germany cancelled Operational Plan Three the same year and decided to focus on creating an empire inside of Europe. But that's another story for another time. Thus, we can only speculate as to what might have happened had the Germans decided to invade America. All we can say for certain is that Teddy Roosevelt would have done something violently awesome, like punch the Kaiser's face in.
Nothing says "Stay on your own goddamn side of the fence!" like a fleet of white and gold battleships.