Founded in Thessaloniki in 1893 under the motto "Macedonia for the Macedonians," and later became the best organized and most renowned Balkan militia. Split into two rival factions after the Ilinden Uprising in Macedonia was crushed by the Ottoman Army in 1903: the Federalists, favouring Macedonian autonomy within a wider Balkan Federation, and the Centralists, fighting for a direct annexation of Macedonia by Bulgaria. The latter faction was led by Ivan "Vancia" Mihailov.
After World War I, continued raids into Macedonia from Bulgarian territory against the new Kingdom of Serbs, Croats and Slovenes, later named Yugoslavia. In March 1923, Bulgarian leader Alexander Stamboliski signed the Treaty of Nis with Yugoslavia, stressing the need for cooperation between the two countries to end IMRO incursions. After a coup forced him from office, Stamboliski fell into the hands of an IMRO contingent, who tortured him, cut off his right hand (which had signed the Treaty of Nis), stabbed him sixty times and decapitated his body.
Following an unsuccessful attempt on the life of King Alexander of Yugoslavia, Ustase leader Ante Pavelic "borrowed" Vancia Mihailov's driver and bodyguard and, together with Dido Kvaternik, plotted to kill the Yugoslav king during a state visit to Marseilles, France using the Bulgarian's expertise. Alexander was assassinated by bullets fired from the revolver held by "Vlada the Chauffeur," as was the French Foreign Minister, Louis Barthou, who was riding in the same vehicle. For this, Pavelic and Kvaternik were sentenced to death in absentia by a French court after Italian dictator Benito Mussolini refused to allow their extradition.
Exasperated by the power IMRO wielded within Bulgaria and of being forced into a hostile position with her neighbours, the governing Zveno movement in Sofia ordered the army to intervene. With the complicity of a moderate IMRO faction, the extremist wing was purged in the mid-1930s, and Vancia Mihailov fled abroad, first to Turkey and later, most probably, to the Independent State of Croatia.
1990: Interview with IMRO leader Ivan "Vance" Mihailov on the murder of King Alexander
OSS File: Croatian Fraternal Union Affairs
April 23, 1942: OSS report on various American Slavic groups; IMRO mentioned by name as a difficult group to infiltrate
CIA File: The Croatian Resistance Movement
June 14, 1948: Mention of Mihailov as a possible agent in connection with the Ustase-backed Krizari movement
