Polish–Ukrainian and Polish–Soviet Wars early 1919.
The origins of the conflict lie in the complex nationality situation in Galicia at the turn of the 20th century. As a result of the House of Habsburg's relative leniency toward national minorities, Austria-Hungary was the perfect ground for the development of both Polish and Ukrainian national movements. During the 1848 revolution, the Austrians, concerned by Polish demands for greater autonomy within the province, gave support to a small group of Ruthenians (the name of the East Slavic people who would later adopt the self-identification of "Ukrainians" or "Rusyns") whose goal was to be recognized as a distinct nationality. After that, Ruthenian language schools were established, Ruthenian political parties formed, and the Ruthenians began attempts to develop their national culture. This came as a surprise to some Poles, who until the revolution believed, along with most of the politically aware Ruthenians, that Ruthenians were part of the Polish nation (which, at that time, was defined in political rather than ethnographic terms). In the late 1890s and the first decades of the next century, the populist Ruthenian intelligentsia adopted the term Ukrainians to describe their nationality. Beginning with the 20th century, national consciousness reached a large number of Ruthenian peasants.
Multiple incidents between the two nations occurred throughout the latter 19th century and early 20th century. For example, in 1897 the Polish administration opposed the Ukrainians in parliamentary elections. Another conflict developed in the years 1901–1908 around Lviv University, where Ukrainian students demanded a separate Ukrainian university, while Polish students and faculty attempted to suppress the movement. In 1903 both Poles and Ukrainians held separate conferences in Lviv (the Poles in May and Ukrainians in August). Afterwards, the two national movements developed with contradictory goals, leading towards the later clash.
The ethnic composition of Galicia underlay the conflict between the Poles and Ukrainians there. The Austrian province of Galicia consisted of territory seized from Poland in 1772, during the first partition. This land, which included territory of historical importance to Poland, including the ancient capital of Kraków, had a majority Polish population, although the eastern part of Galicia included the heartland of the historic territory of Galicia-Volhynia and had a Ukrainian majority. In eastern Galicia, Ukrainians made up approximately 65% of the population while Poles made up only 22% of the population. Of the 44 administrative divisions of Austrian eastern Galicia, Lviv (Polish: Lwów, German: Lemberg), the biggest and capital city of the province, was the only one in which Poles made up a majority of the population. In Lviv, the population in 1910 was approximately 60% Polish and 17% Ukrainian. This city with its Polish inhabitants was considered by many Poles to have been one of Poland's cultural capitals. For many Poles, including Lviv's Polish population, it was unthinkable that their city should not be under Polish control.
The religious and ethnic divisions corresponded to social stratification. Galicia's leading social class were Polish nobles or descendants of Rus' gentry who had become polonized in the past, whereas, in the eastern part of the province Ruthenians (Ukrainians) constituted the majority of the peasant population. Poles and Jews were responsible for most of the commercial and industrial development in Galicia in the late 19th century.
Throughout the 19th and early 20th centuries the local Ukrainians attempted to persuade the Austrians to divide Galicia into Western (Polish) and Eastern (Ukrainian) provinces. These efforts were resisted and thwarted by those local Poles who feared losing control of Lviv and East Galicia. The Austrians eventually agreed in principle to divide the province of Galicia; in October 1916 the Austrian Emperor Karl I promised to do so once the war had ended.