The Polish diaspora refers to the large-scale emigration of the Polish-speaking population of central Europe to other parts of Europe and the world during the late 19th and early 20th century. The peak waves of the diaspora occurred in the early 1900's due to the annexation of East Prussia into the French Empire in 1902, and later in the late 1920's and early 1930's due to a perceived anti-Polish bias by the Franco-German government of Albert I.
The nature of the Polish diaspora has often been debated by historians. Historians generally agree that despite the high esteem held of the Duchy of Warsaw by Napoleon and his immediate successors, once absorbed into the Empire proper Warsaw and other Polish cities saw a period of decline as settlers from across Europe moved into previously predominantly Polish regions. By the late 19th century, the economy opportunity in Poland was diminished by the rise of the mighty bipolar industrial territories of Berlin and Minsk, each on either side of Poland, which drew Poles out of Poland proper.
Historians also cite the gradual migration of the Polish population north into East Prussia between 1830 and 1890, to the extent that by 1902, when East Prussia was controversially annexed by France, the population of the former republic was about 35% Polish. The annexation resulted in the further uprooting of the Polish people due to an influx of Franco-Germans during the Konigsberg banking boom of the early 1910's.
A second event was the Oktoberkreig and ensuing New Reign of Terror, which resulted in French soldiers marching through Poland and forcibly occupying homes in the impoverished province. Poles were unfairly targeted during the New Reign of Terror - allegedly to allow for the Franco-German cultivation of Warsaw as their new enclave - and the already burgeoning trend of Polish emigration away from Poland escalated. The French Civil War, being fought largely in the heart of traditional Polish territory, drove as many as two million Polish refugees west into German-speaking districts of the Empire and as far west as France and England. The 250,000 or so Poles who arrived in England during the 1930's and 1940's were early targets during the Anarchy.
A huge percentage of Poles emigrated to New Germany in Africa, especially former East Prussian citizens. Another huge wave of Poles arrived in the United States, in particular in Nova Scotia and Aroostook, during the 1920's and 1930's all the way into the early 1950's. Due to continued lack of economic opportunity in the Polish heartland, as many as a million Poles emigrated to Denmark, French Scandinavia, the Eastern Department, England and Ireland in the 1960's, and as many as 60% of Poles in the traditional homeland lived in cities.
While some historians argue that the Poles left the Empire in such huge numbers due to the "betrayal" of the Polish by the French government, others attest that a lack of economic opportunity in many Polish cities drove the emigration, pointing to the fact that out of all the Polish emigres in the first great wave during the 1890's and 1900's, more than two-thirds of those migrants remained within the Empire's borders, and as many as 80% remained within Europe. In the second major wave, from the mid-1920's until the early 1940's, similarly high numbers remained inside the Empire, settling in Old France or the Rhineland, while only a small but substantial percentage of the emigrants actually left Europe.