How significant was America breaking the stalemate in ww1?

Answer 1

Not very. The Royal Navy (of the United Kingdom) had managed to achieve a blockade of Germany and was effectively starving the nation of all resources it could only achieve through importing. France, Britain, and Italy were worn down and hadn't made any geographical progress, but Germany had less manpower and industrial capacity combined. The fuel shortage and harsh winters of 1917 made a severe impact on both sides on the home front, many civilians were killed simply due to being unable to warm themselves. However, with the American declaration it had pretty much sealed victory against Germany and Austria-Hungary. Their conspiracy with Mexico had achieved the worst possible results, Mexico didn't declare war and join the German Alliance but the negotiations had been uncovered with the decoding of the Zimmerman Telegram. Instead of creating a war between Mexico and the US, it had only brought another enemy against them. This only gave the Kaiser the view that the Great War was inevitably lost, with his abdication lesser German politicians were forced forward to assume command and pushed for the peace deal known as the Treaty of Versailles. The Great War wasn't ended because one side militarily collapsed or was defeated, but the idea (rightly or wrongly) that the war could only be lost was strengthened by a number of factors, America joining the war against them being one of the many. A rapidly degrading economic sitation could be seen to be far more dire for the German war effort.