The Reichsmarine was the naval fleet of Germany during the Weimar Republic (1919-1933). It was created right after World War I, with a limited number of warships due to the fact that the Treaty of Versailles had imposed such restriction. Along with the German Army (das Heer), it was a part of the Reichswehr, which was the name of the German armed forces during this period. Thus, it succeeded the Kaiserliche Marine (the Imperial German Navy), which had been formed when the German Empire was created in 1871 at the end of the Franco-Prussian War.
The Reichsmarine was created in 1919, practically from scratch, as 74 warships of the Kaiserliche Marine had been scuttled by their commander in Scapa Flow, right after Germany had surrendered, to prevent that these ships fell in British hands. (Scapa Flow is a body of water in the Scottish Northern islands). This is how Germany formed the Reichsmarine, around what was left at their naval ports; a handful of obsolete warships: 12 destroyers, six light cruisers, and six dreadnought battleships, which had been built at the beginning of the 20th century. They had not been kept in proper conditions, with old rusting boilers and machinery.
Reduced in tonnage and to only 20,000 men, the only mission and purpose of the Reichsmarine was the defense of Germany's coastline, with their first commander being Admiral von Trotha, who would be succeeded by Admiral Behnke. However, in the mid 1920s, these war vessels would be upgraded and modernized. Therefore, the dreadnought battleships Schleswig Holstein, Schlesien, and Hessen were still in service when Adolf Hitler became Chancellor in 1933. With the creation of the Third Reich, a new navy would be formed; the Kriegsmarine, whose most feared vessel would be the U-boat.
Below, the Schlesien and Schleswig-Holstein dreadnought battleships of the Reichsmarine anchored in a German deep-water river in 1925.