lutionary Organisation (ITRO).
In the early organization the membership was allowed only for Bulgarians, but later it was opened to all inhabitants of European Turkey, regardless of their nationality or religion. The majority of its members however were Macedonian Bulgarians In 1903, IMRO organised the Ilinden-Preobrazhenie Uprising against the Ottomans, which after some initial successes, including the forming of the "Krushevo Republic", was crushed with much loss of life. The uprising and the forming of the Krushevo Republic are considered the cornerstone and precursors to the eventual establishment of the Macedonian state.
Kingdoms of Serbia and Yugoslavia
Following the two Balkan wars of 1912 and 1913 and the dissolution of the Ottoman Empire, most of its European held territories were divided between Greece, Bulgaria and Serbia. The territory of the modern Macedonian state was then named Južna Srbija, "Southern Serbia". After the First World War, Kingdom of Serbia became part of the Kingdom of Serbs, Croats and Slovenes. In 1929, the Kingdom was officially renamed the Kingdom of Yugoslavia and divided into provinces called banovinas. Southern Serbia, including all of what is now the Republic of Macedonia, became known as the Vardar Banovina of the Kingdom of Yugoslavia.
The concept of a United Macedonia was used by the Internal Macedonian Revolutionary Organization (IMRO) in the interbellum. Its leaders – like Todor Alexandrov, Aleksandar Protogerov, Ivan Mihailov, promoted the idea with the aim to liberate the territories occupied by Serbia and Greece and to create an independent and united Macedonia for all Macedonians, regardless of religion and ethnicity. The Bulgarian government of Alexander Malinov in 1918 offered to give Pirin Macedonia for that purpose after World War I, but the Great Powers did not adopt this idea, because Serbia and Greece opposed.
IMRO followed by starting an insurgent war in Vardar
