[1] It roughly comprised the incoherent territory of the former Principality of Brunswick-Wolfenbüttel, stretching from Holzminden on the Weser River in the west to Blankenburg in the Harz mountain range and Calvörde in the east.

However, their intentions to implement a Soviet republic failed, as in the first parliamentary elections on 22 December 1918 the USPD officials were outnumbered by the Social Democrats (SPD), who reached 27.7% of the votes cast.

[6] On 22 February 1919, both parties formed a coalition government led by the USPD politician Joseph ("Sepp") Oerter,[7] that shifted the state's constitution towards a parliamentary republic.

Four days later, the Reich government declared the state of emergency in Brunswick and crushed the Spartacist revolt with the aid of invading Freikorps troops under Georg Ludwig Rudolf Maercker.

However, in the 1920 state election, the SPD suffered a heavy loss of votes and the succeeding coalition government was again led by his USPD rival Sepp Oerter.

In the 1922 elections, the SPD/USPD government finally lost its majority, whereafter the Social Democrats under Heinrich Jasper formed a coalition with the DDP and the national liberal German People's Party (DVP).

The NSDAP reached 22.9% of the votes cast, whereafter the Nazi politician Anton Franzen joined the new right-wing government as Minister of the Interior,[10] succeeded by his party fellow Dietrich Klagges on 15 September 1931.

This dissolved all the sitting Landtage and reconstituted them on the basis of the recent 5 March 1933 Reichstag election results, which had given the Nazi Party and its coalition partner the DNVP a working majority.

The Brunswick territory became part of the British occupation zone, with the exception of the eastern Blankenburg and Calvörde areas, which fell to Soviet-administered Saxony-Anhalt.