To further explain my points out:
Paris 1919: Six Months That Changed The World, Pg 159:
And the Allied forces were shrinking were shrinking. In November 1918, there were 198 Allied Divisions; by June 1919, only 39 remained. And could they be relied upon? There was little enthusiasm for renewed fighting. Allied demobilization had been hastened by protests, occasionally outright mutiny. On the home fronts, there was a longing for peace, and lower taxes. The French were particularly insistent on the need to make peace while the Allies could still dictate terms.
While his pessimism was premature, it is true by the spring of 1919 Allied commanders were increasingly doubtful about their ability to successfully wage war on Germany. The German Army had been defeated on the battlefield, but its command structure, along with hundreds of thousands of trained men, had survived. There were 75 Million Germans and only 40 million French, as Foch kept repeating. And the German people, Allied observers noticed, were opposed to signing a harsh peace. Who knew what resistance there would be as Allied armies moved farther and farther into the country? They would face, warned the military experts, a sullen population, perhaps strikes, even gunfire. It was very unlikely the Allies could get as far as Berlin.
Previously on Pg 158:
Among the Allied leaders only General Pershing, the top American military commander, thought the Allies should press on, beyond the Rhine if necessary. The French did not want anymore of their men to die. Their chief general, Marshal Foch, who was also the supreme Allied commander, warned that they ran the risk of stiff resistance and heavy losses. The British wanted to make peace before the Americans became too strong. And Smuts spoke for many in Europe when he warned gloomily that "the grim spectre of Bolshevist anarchy was stalking the front."
Expanding on that Smuts quote, is important to note that there
was reoccurring unrest and mutiny in the Royal Navy throughout 1919 and mutinies had begun to breakout among the Entente forces by September of 1918. While the Americans were indeed landing more and more forces each day, these men were green troops who were about to, due to Anglo-French weakness, be sent into the meat grinder that was coming. To quote from Paddy Griffiths's
The Great War on the Western Front: A Short History (Pg. 128):
However, what Pershing overlooked was that ever since 1871 Metz had been fortified to at least the same standard that the French had applied to Verdun during the same period. To attack Metz in 1919 would have been equivalent to selecting the very strongest point in the enemy line on which to beat one's head.
Essentially, the AEF was looking at a bloodbath going into 1919 and I seriously doubt American morale could withstand such; their rapid drawdown of forces by early 1919 and the following rejection of the Treaty of Versailles shows where the political headwinds were already in favor of, and 500,000 dead Doughboys would certainly amplify such.
With regards to German morale, John Keegan in his book
The First World War (Pg 421) states that:
The army at the front, after its brief morale collapse in late September, when troops returning from the trenches had taunted those going up with cries of "strike breakers", had indeed recovered something of its old spirit and was contesting the advance of the Allies towards the German frontier. In Flanders, where water obstacles were plentiful, the French were held up, to Foch's irritation, for some time.
He later states that (Pg 423):
by the first week of November, therefore, the German Empire stood alone as a combatant among the war's Central Powers. Under pressure from the French, British, Americans and Belgians, the army's resistance stiffened as it feel back across the battlefields of 1914 towards Belgium and the German frontier. There was hard fighting at the rivers and canals, casualties rose-among the penultimate fatalities was the British poet, Wilfred Owen, killed at the crossing of the River Sambre on 4 November-and the war, to the Allied soldiers battling at the front, seemed to threaten to prolong.
Enduring the Great War: Combat, Morale and Collapse in the German and British Armies, 1914–1918 by Alexander Watson notes on pg. 210 that Crown Prince Rupprecht (Commander of the 7th Army) and
Generaloberst Karl von Einem (Commander of the 3rd Army and former Prussian War Minister) both do not mention desertion as becoming an issue until October. He further states that there is no evidence for mass numbers of deserters until the last three or four weeks of the war, at which time the
OHL had to reinforce the military police with five squadrons of cavalry. Even still, Watson decisively refutes the notion that there was a million deserters by the time of the Armistice and further notes that little desertion was occurring by the combat units at the front who were resisting quite strongly as Keegan wrote. Going into 1919, the Germans had managed to crush their own Bolshevists by June. In February, the Freikorps had managed to likewise defeat the Poles and reclaim Poznan until Entente pressure forced them to pull out once more. Likewise, a force of about 50,000 under General von der Goltz had managed to occupy the Baltic states and eject the Red Army; Entente pressure on Berlin forced them to return large numbers of von der Goltz's troops, while British supplies and naval gunfire support allowed the Balts to kick the reduced force out soon after. I think all of this, quite clearly, shows the Germans were more than able to fight it out morale wise.
Food situation was also improving over the course of 1918, and average calories in rations actually increased. Further relief was expected going into 1919, as Ukraine had finally been secured in the Summer of 1918 and it could be reasonably expected that food would begin to arrive from there sometime in 1919; I've seen April as a likely projected date. On this note, further, the armistice actually made the food situation
worse as the Germans were required to surrender vast amounts of food stored within military depots and the entry of the British into the Baltic led to the closure of the Baltic ports and their fishing fleets. It's often forgotten, but the Blockade was continued into March of 1919 fully and into a restricted mode all the way into July.
The German Offensives of 1918 by David T. Zabecki also states that existing stocks of ammunition were more than sufficient to meet continued needs, artillery production actually had to be decreased due to overproduction, and small arm production was likewise sufficient over the course of 1918. Expected manpower intakes were to be between 600,000 to 700,000 men in the fall, and he does state this is might not be enough to meet expected demands but the defensive nature the Germans were adopting would probably offset this. Should the need arise, however, the Germans could begin extending war work to women which could free up over a million German men for service; many were ex-veterans who had been sent home as a result of the Hindenburg Program. On the whole, I'd also rate the German material position as conducive to fighting it out as well.