From am earlier answer of mine

"Preparing for war" is not quite the correct word to describe Weimar's military and political policies. While there were certain lines of continuity between Weimar's clandestine rearmament and the Third Reich's, the latter dictatorship's motives were more aggressive in intent and comprehensive in scope.

The Weimar military, the Reichswehr, certainly did lay down long-range plans to scupper the Versailles Treaty and rearm. The Truppenamt (personnel office) operated as a de facto general staff, which the Versailles Treaty had prohibited, and its officers envisioned a rapid expansion of the military. Some of this evasion was planned via dishonest means that violated the spirit of the Treaty. For example, the Truppenamt managed its officers so that they could be rapidly promoted; eg lieutenants receiving training for a captain's job. This personnel policy meant that the Reichswehr had a massive officer base for expansion beyond the 100000 man limit set by the Allies. Other evasions were more serious breaches of the Treaty such as clandestine development of military aircraft both within Germany and the USSR. The Soviets, along with other parties like the Japanese (who were actually part of the Allied powers enforcing the Treaty), sought out German expertise in developing tanks or submarines. For their part, the Reichswehr got to keep abreast of global military technology.

But these open violations of the Treaty paled before the rearmament undertaken by the Third Reich. The Kazan tank school had provided the Germans with valuable technical experience and training, but Hitler's rearmament drive was far more beneficial to German tank development in that it actually brought real tank development within Germany. Hitler's rearmament drive poured resources into weaponry that far exceeded even the wildest dreams of the Truppenamt. The late-Weimar Reichswehr had envisioned a twenty-one division post-Versailles peacetime army by 1938. Hitler envisioned a much grander army; his meetings with the military chiefs in 1933 called for the twenty-one division benchmark by 1935 and exceeding it afterwards. German rearmament proceeded after 1933 at a breakneck pace and the newly rechristened Wehrmacht struggled to meet the demands for ever-larger planned armed forces. The carefully-planned officer scheme of Reichswehr could not match this expansion. One of the problems for the peacetime Wehrmacht was there simply were not enough officers to man these new formations and the training establishment could not keep up with demand.

The ease at which Hitler rearmed underscores the weaknesses of the Versailles system. The Treaty may have been quite stringent, but there were no effective mechanisms to enforce its provisions. The divided Allied leadership simply could not form a united front to stop any German evasions of the Treaty. The Reichswehr's clandestine actions were less secret than the term clandestine implies. There were numerous exposes of these efforts both in the Western European press and the German newspapers. A number of Weimar statesmen like Gustav Stresemann recognized that Versailles was a paper tiger and that they could maneuver a renegotiation of the Treaty if they played their political cards correctly.

Hindsight shows the sagacity of the Stresemann approach to patchwork revision of the Treaty system like Locarno over Hitler's open abrogation of it. Hitler's rearmament drive may have been evading a toothless Treaty system, but it was also expensive and painted Germany into an isolated diplomatic corner. Germany managed to finance its extensive rearmament through various fiscal chicanery like MEFO-bills and the later expropriation of Austrian and Czech assets.

The more cautious revisionism of Stresemann also underscores that Weimar politicians also operated in a more constrained domestic political environment than Hitler. While there certainly were nationalistic and militaristic elements within Weimar society, there were also antiwar elements as well. Prussia, for example, became one of the electoral backbones of the SPD. Käthe Kollwitz and Erich Maria Remarque were just two examples of Weimar's vibrant peace movement and they were not isolated figures in Weimar culture. The Reichstag's debates over the Panzerschiffs in the late 1920s and 30s illustrated how open rearmament was not an uncontentious issue within Germany. An SPD-led Reichstag bill to cancel the first of what became known as "pocket battleships" only narrowly failed to pass the legislative body.

The Panzerschiffe did end up being built and proved a nucleus for a future German surface fleet under Hitler. This does show that the Weimar did provide a foundation for the latter rearmament. The Truppenamt certainly did plan for an enlarged peacetime army and some nationalists floated ideas of regaining Germany's lost territories such as the Polish corridor. But formulating these ideas and putting them into practice were two different things. Weimar's rearmament was always a divisive political issue and one that was the cause of considerable domestic squabbles. Hitler operated with the benefit of eliminating his political opposition and sidelining his allies in the German right. The Reichswehr soon found Hitler's rearmament drive to be a Faustian bargain as the Nazis gave them too much of what they wanted too quickly.

Sources

Corum, James S. The Roots of Blitzkrieg: Hans Von Seeckt and German Military Reform. Lawrence, Kan: University Press of Kansas, 1992.

Habeck, Mary. Storm of Steel. Ithaca: Cornell University Press, 2014.

Peukert, Detlev. The Weimar Republic: the crisis of classical modernity. New York: Hill and Wang, 1992.