(1) they believe there field armies are on the brink of total collapse ( Even if the "actual" state of the field armies is not so dire it is of little relevance) Those who direct its operations are now actively considering defeat. This could be seen as defeatism but it is born from actual real time events.
(2) Economically the ability to continue supplying troops and material is coming to an end.
(3) The possible invasion of German Territory (that the allies may not have the strength is again irrelevant) German Authorities now believe this is a possibility.
(4) Even though they believe there military may have strength for a defensive last stand on Germanys borders they are unsure as to the sustainability of this. The amount POW`s siezed by the Allies in 1918 would have influenced this.
There are many other of these "indicators of looming defeat". But the acceptance of the armistice terms how ever harsh they may have been is the clearest indicator that Germany actively and intellectualy lost the war in 1918.
He got a pullitzer prize for this work of fictionIn The Myth of the Great War, Mosier argues that Germany was winning World War I, and only the arrival of the United States spared the Allies from military defeat and a negotiated peace with the Germans.
I do not agree with this, (None of Germanys tactical successes equalled a war winning strategy ) but i do believe that going into 1918 the outcome was quite finely balanced. But we are talking about an evenly fought war of offense followed by defense (very classic formula) in which all sides struggled to gain an advantage. got tired and worn out and faced huge problems, thats why there are so many differing hypothesis as to who was winning at which point (this because of numerical parity on many issues). Mosier though does not prove in any way that he is correct, in fact he never does in any of his books he just says this is how it was. And then does not substantiate his claims.
And if Germany was winning going into 1918 then Ludendorff shot his bolt badly as he wasted a near million soldiers on ineffective offensives which did not achieve there aims. Germanys largest problem was always that they could only win WW1 on the western front. An armistice in the east only gave them a military opportunity to launch a full scale offensive in the west and they failed which broke Ludendorffs nerve.
Being British i always rate the intervention of the US in both World Wars,(thanks cus) and American troops were beginning to flood into France but the balance of the fighting was still in the hands of the French /British/Commonwealth troops.. ably assisted by the Americans and the threat of rising troop numbers had an obvious impact but it was one of a number of reasons which induced fear and cowardice through the ranks of the Bosch invaders and its vaunted Gross General Stab (sorry bit of revisionist British rhetoric)
ps did the Russians not sue for an armistice in the east ?????? was that not considered a victory by Germany ...