Neutrality

On this day in 1917, President Woodrow Wilson asked Congress to declare war on Germany. At that point in time, World War I was already nearing its third birthday; millions had already been killed, including 128 Americans aboard the torpedoed ship the HMS Lusitainia. Germany had announced their intention to pursue unrestricted submarine warfare, granting itself license to sink any ship, any where in the ocean in January.
Congress complied with Wilson's request four days later on April 6.
No rush.

(It was not until only months before the armistice that American troops began arriving in significant numbers. Of course this lends credence to the argument that the arrival of the American military turned the tide.)