Einigkeit: The Weimar Republic is a timeline where the Weimar German republic lasts and does not fall to the national socialist movements of the time, and survives to this day.
The short of this timeline is that the Cuno government falls in 1922, replaced by Gustav Stresemann, who negotiates a more favorable reparation scheme, allowing the German economy to stabilize more quickly. The Beer Hall Putsch occurs, but Hitler is one of the 16 shot, leading to the fracture of the NSDAP into north and south branches which then get absorbed into other parties, while the Hamburg Uprising in October claims Ernst Thälmann, one of its leaders, who is unable to split the left's vote in 1925, resulting in Wilhelm Marx gaining the presidency instead of Hindenburg.
Germany under Marx joins the League of Nations in 1926, and organizes a plebiscite in Danzig in 1933 over rejoining Germany, which it wins. Piłsudski's government turns more totalitarian, while Germany under Marx, then Ebert again, enjoys more favorable relations with the west. In 1938, Dollfuss, the fascist dictator of Austria, attempts to start a rebellion in Bavaria, which leads to German military intervention in Austria, toppling the government. Despite the Versailles Treaty ban on Anschluß, the Germans in Austria vote to join the free, democratic, and prosperous Germany of the north.
Poland, growing more totalitarian, finds friends in France, Romania and Italy, all more totalitarian in this timeline. Poland proposes to France a preventive war on Germany, with France occupying the Rhine, and Poland retaking Danzig and Silesia, which would enrich both countries. After securing a Soviet-Polish non-aggression pact and a French-Polish treaty, Piłsudski uses a staged diplomatic incident to start a war with Germany, demanding Danzig and all Upper Silesia or risk total war. PM Chamberlain from the UK visits Warsaw, and returns to the United Kingdom, now pacifist, with a paper proclaiming 'peace in our time' in 1938. When Poland rolls into German Silesia in 1939, with the Poles remaining in Upper Silesia and Danzig greeting them as liberators, the Germans find themselves outgunned as a result of Versailles, even with their re-armaments.
France sweeps into Belgium and through Alsace-Lorraine, sparking British outrage at the violation of Belgian neutrality. Spain, having its own fascist revolution aided by France, and Portugal, under the Estado Novo aided France, while Greece sided with Britain, Bulgaria with Poland, and Yugoslavia with Britain.
The UK gears up for war to aid Germany, while Poland and France seize the initiative and strike Germany. The Rhine and Silesia put up resistance to the invasion, while forces try to mobilize and a draft is put into effect. Its army increases from 175,000 to 385,000 in the span of two months. Industry in Silesia, Saxony, and Brandenburg turns to the war effort.
France pushes from the Rhine into Hanover and north, also absorbing the Netherlands, while Poland pushes into East Prussia, Upper Silesia, and Danzig, which are forced to surrender to the Poles by mid-1940. The British begin air raids on France, while the French return the favor with air raids on Berlin. British forces in the Mediterranean meet resistance, but are aided by the Greeks on the east from Cyprus, while the Turks try to use the war to regain eastern Thrace from them.
France, Poland and Italy meet in secret to discuss Europe's borders, where France includes Belgium, Luxembourg, Rhineland, Netherlands, Hanover, and Hamburg; Poland includes everything east of the Oder-Neisse rivers, and Italy controls the Balkans.
Italy moves into Yugoslavia and Slovenia, Poland into Pomerania and Lower Silesia, and France into Hanover. The British make landfall in Germany, and attempt to do so in Portugal, but are rebuffed. By 1941, Japan attacks the US and draws it into the war.