Along with the Province of Posen, Kreis Birnbaum became part of the German Empire in 1871. With effect of 1 October 1887, its westernmost part, including Schwerin an der Warthe and Blesen was separated as Kreis Schwerin an der Warthe.
In the aftermath of the German collapse on the Western Front in World War I, the Treaty of Versailles awarded most of the province, including Kreis Birnbaum, to the new state of Poland. The handover was executed by between 17 January and 4 February 1920.
Demographics
Before the bifurcation of the district in 1887, it had a German majority population. According to the Prussian census of 1860, it had a population of 45,425, of which 34,608 (76.2%) were Germans and 10,817 (23.8%) were Poles.[1] The district population, after the separation of the predominantly German Kreis Schwerin was almost evenly split among Germans and Poles.[1]
In 1833 the office of a Wójt (Vogt, reeve) was established in the districts of the predominantly Polish-settled Grand Duchy of Posen, a voluntary administrator who often was a member of the local nobility. However, in the course of the Prussian Germanisation policies under Governor Eduard Heinrich von Flottwell, they were replaced by Prussian commissioners. In 1905, the municipalities in Kreis Birnbaum were governed within three police districts (Polizeidistrikte):
