How long was the united states spending in world war 1

they were in the war for 1 year, 7 months , and 6 days (or simply 568 days)

939 --- The war begins as Poland falls to Germany. 1940 --- France, Hollband, Belgium, Norway, and Denmark fall to Germany. Italy enters the war on the Axis side, attacks Great Britain in North Africa, and invades Greece. German invasion of Great Britain is planned but never occurs.