American government-to-government loans had been crucial to maintaining the Allied war effort from February 1917 onwards, the British and French having used up most of their credit with their American creditors.

However, in terms of actual military contributions to the defeat of the Spring Offensives, the answer is no. Michael, Georgette, Gneisenau and Mars were seen off by British and French forces. American forces were involved considerably in the defense against the Friedenstum and in the subsequent Second Battle of the Marne, but by that point (July 1918) the Germans had already shot their bolt. Even in those two cases I mentioned, French and colonial troops outnumbered Americans.