The Germans thought they were about to defeat the Entente, in reality, they didn't come close. Germany was slowly collapsing along with Austria-Hungary, Bulgaria and the Ottomans, capturing Paris in 1918 with the USA in the war wouldn't have saved them.
As previously noted, it doesn’t really matter whether the Germans were on the brink of victory or not. What matters is that they certainly
believed that they were (as did many on the Allied side - see below), and it is their perception more than the reality which will shape their memories of the war.
As to whether Allied victory was assured or not, all I can say is that it didn’t look that way to many of the Allies themselves. Pétain’s remark in March that "The Germans will defeat the English, and after that they will defeat us" is well known, as is Haig’s April "Backs to the wall" message, in which he declares that "every one of us will fight on to the end", hardly the language of a man who thinks defeat is impossible. Less famous examples include
1) John Toland (
No Man’s Land, Ch 8) recounts that on June 9, 1918
"Major Lloyd Griscom was preparing to leave the capital for London on a special mission for Pershing, and stopped at the French War Ministry for the latest information. He found utter despondency, and the Chief of Staff, a perfect stranger, began pouring out his despair. "France is on the brink of catastrophe," he exclaimed. "She is exhausted. Every bayonet is at the front line, we’ve drained our factories of their best workmen, we’ve crippled our service of supply, our railroads can hardly operate." He continued in this vein for almost an hour - - -
"If you will you can render us a great service. You see, the British take the war differently from we do. Their able-bodied men by the thousands are mining coal to sell at a profit all over the world. In their munitions factories they have far more healthy sound men than they need. It is well known the number who can go on their fighting fleet is limited, yet their navy is crowded. Now is the moment for forcing the
embusqués [soldiers not at the front line] into the battle lines of France. But we cannot make them comprehend our desperate straits." - - -
Griscom - - - left Paris for Pétain’s headquarters at Chantilly. The General was away but his Chief of Staff, Geenral Anthoine, spoke openly "All is lost!" he told Griscom. "Nothing can save Paris! Nothing! Griscom tried to calm him by saying that Pershing felt quite the reverse and that Anthoine’s own superior at the war Ministry wasn’t that gloomy. What do they know about it? It is we who are fighting the war who know. You as a stranger can have no idea what losing Paris means. Paris is not only our capital, but also our greatest manufacturing city. Without it we are lost." Every Frenchman realised that. - - -
Similar panic was also spreading among the British leaders in London. That day Lord Milner wrote Lloyd George:
"- - - We must be prepared for France and Italy both being beaten to their knees. In that case the Germans-Austro-Turks-Bulgar bloc will be master of all Europe and Northern and Central Asia up to the point at which Japan steps in to bar the way, if she does step in . . .
In any case it is clear that, unless the remaining free peoples of the world, America, this country, and the Dominions, are knit together in the closest conceivable alliance and prepared for the maximum of sacrifice, the Central Bloc . . . will control not only Europe and most of Asia but the whole world."
2)
The Life and Letters of Walter Hines Page [1] includes the following memorandum of June 10, 1918
The Germans continue to gain ground in France - more slowly, but still they gain. The French and British papers now give space to plans for the final defense - the desperate defense - of Paris. The Germans are only forty miles away. Slocum, military attaché, thinks they will get it and reports the same opinion at the War Office - because the Germans have taken such a large number of guns and so much ammunition. Some of these guns were meant for the American troops, and they cannot now be replaced in time if the German advance continues. But I do not know enough facts at first hand to form an opinion. But, if Paris be taken, the war will go on for a long time - unless the English-speaking rulers make a compromise. And then, in another form - and forms - it’ll go on indefinitely. - There has been no more perilous or uncertain or anxious time than now.
The United States too late, too late, too late; what if it should turn out so?"
3) In
A Bridge To France (Ch XIV) Edward N Hurley, Chairman of the United States Shipping Board during WW1, recounts a remarkable conversation with
President Wilson.
"The seriousness of this situation was impressed upon me by the President when he requested that a special survey be made of cargo-ships that could be furnished - - - for the transportation of food and material supplies for the increased number of troops to meet the pressing demands of the Allies.
"Hurley" he said, "with the success of the Germans in driving a wedge between the well-seasoned troops of the British and French in the Cambrai sector, if by any chance they were to repeat their onslaught with a like result on our front and capture a hundred thousand or more of our soldiers, I dread to contemplate the feeling which would be produced in the mind of the American people. Unless we send over every man possible to support the Allies in their present desperate condition, a situation may develop which would require us to pay for the entire cost of the war to the Central Powers". [2]
He sat gazing intently out of a window towards the green fields across the Potomac; but he did not see the beautiful landscape which lay before him. What he saw was a vision of the bloody battlefields of France! He was thinking intently and earnestly. I did not interrupt his meditation. When he turned toward me again his face was pale and his features were drawn. Calmly but firmly he said, "Hurley, we must go to the limit.""
If the Germans were mistaken in believing victory to be in sight, their misapprehension was shared by a lot of important (and presumably well-informed) men on the other side, apparently including the President of the United States.
[1] Page was US Ambassador in London, 1913-18, and had been passionately pro-Ally right from the start of the war, long before there was any question of the US entering it.
[2] Hurley doesn’t indicate Wilson’s reason for believing this, but the likeliest would be that such a large number of captured Americans would be in effect hostages, held indefinitely as prisoners of war until the US signed up to a peace on German terms. In the same way, OTL, the Allies held on to their German prisoners until after (indeed many months after) Germany had signed the Treaty of Versailles. So the idea is not fanciful.