As a multiethnic and multicultural state, the Second Republic had quickly to address a series of leading questions about how best to establish a positive relationship with those of its citizens, approximately one in three, who did not regard themselves in any meaningful way as being 'Polish'. Were the five or six million Ukrainians, over three million Jews, one and a half million Byelorussians and some 800,000 Germans to be encouraged to assimilate and thus to become wholly 'Polish' over time, or were they to be assimilated only to a certain degree and permitted to retain in some sense a dual national consciousness? The answer was provided from several sources. In the first instance, the concept of the nation-state was almost universally accepted in Europe after 1918 and had been a crucial part of the postwar peace settlement, so that nationalist sentiment was running at historically high levels.
In Poland, specifically, there were in addition political pressures, articulated most vociferously, but by no means exclusively, by the Endecja, to construct a strong country in which the non-Polish minorities should not be allowed to constitute an impediment to the realisation of this goal. Dmowski's prescription of an integral Polish-Catholic nationalism was designed to form the basis of a unitary state. For a while, the Piłsudski camp, in trying to resurrect within a democratic framework a modified version of the old Polish-Lithuanian Commonwealth, adopted the softer line of favouring a supranational, federalist Poland. But it soon came unstuck in the face of the early postwar turmoil and powerful manifestations of nationalism from the minorities which now found themselves incorporated into Poland. The other Polish political parties generally formulated variations of what the Endecja and Piłsudski camp offered, with a few striking exceptions; for example, the Communists, who did not recognise the validity of the Polish State in the first place. Some parties, including those representing the peasantry, paid at least lip service to the principle of minority rights, and endorsed with varying degrees of