Operation Michael succeeds and the germans take Amiens. The Allies panic and an offensive is launched that summer, spearheaded by the American that just arrived to Europe. It is a complete disaster, and Wilson lose all political capital due to that, with the public feeling that they've been tricked to enter the European meatgrinder for nothing. To regain public support, Wilson begins pressuring Great Britain and France to make peace with Germany.
Germany gets Camerun (with the borders from before the Moroccan Crisis and minus the british occupied part), Togoland and East Africa back; also annexes Luxemburg and establishes puppet monarchies in Ukraine, the Baltic, Lithuania and Poland. Asutria Hungary gets out with Status Quo (except for Sandjak, which it's annexed into Bosnia), and Turkey is left to the tender mercies of the Entente. Bulgaria gets San Stefano borders.
The Reds win the Civil War in Russia, taking control of more or less modern Russia, Belarus and Central Asia.
In the early 20's A-H collapses from ethnic strife. Germany moves in and manages to install a puppet king in Hungary and in Croatia. Austria and Bohemia are (separately) absorbed into the Reich, with autonomy similar to that of Bavaria. The Italians and the Serbians, which have both gone fascistish, move into Bosnia. The Germans try to install a puppet king in Bosnia too, and it all quickly descends into a three-way war. The stalemate lasts for 1-2 years, and eventually a settlements is reached, where Serbai gets an autonomous Bosnia, Italy gets Dalmatia and Germany Croatia. Germany accepts basically because troops are needed in the East and in Hungary, to put down nationalist and Red uprisings.
Troubles don't end there for Germany. Ethnic conflict continues in Hungary, needing of permanent german garrisoning in Transylvania, Banat and Slovakia. Troops are also sent to Eastern Europe for similar motives. Togoland is eventually sold to pay for all this, the promised wealth of Eastern Europe never reaching Germany due to constant guerrilla. Unrest grows with the growing bodybags coming from the East with german corpses inside them. Due to the growing popularity of the KPD elections are suspended and a State of Emergency declared.
Eventually some war vet from the Great War or the occuppation of the East and Hungary creates a fascist party, with string emphasis on german cultural identity and the primacy of the german people (I see it more along Italian lines rather than close to Nazism). He believes that the current problems of Germany are due to foreign agents allied with leftist intelligentsia, all of it orchestrated by a secret alliance of the bankers and capitalists of London and Paris and the Godless communists of Moscow, to try and destroy Germany through sabotage and subterfuge, as they couldn't through open war (proving german superiority). The party's popularity grows among vets and conservative folk, and eventually the Emergency Government (probably dominated by an alliance of the military and rightist parties like DNVP) allies with them, allowing elections to take place. The KPD remains banned, and the DNVP+the Fascist Party win the elections. Eventually the fascists take over the government and/or the DNVP.