The IMRO was established in 1895 as a movement for the autonomy of Macedonia
within either the Ottoman Empire or a federation of Balkan States. Right from
the beginning it was challenged by the Supreme Macedonian Commmittee, which sought
to annex Macedonia for Bulgaria. This group gained control of the IMRO in 1921
and began terrorist operations in the Yugoslav section of Macedonia,
sunsequently securing considerable influence over Bulgarian politics.
In 1924, following the way of many militant groups, the IMRO split into two hostile
factions, which indulged in an orgy of assassination, tempered by raids
across the Greek and Yugoslav frontiers that seriously endangered
the peace on the Balkans. The activities of the group died down after 1934, partly because
of the opposition of a new Bulgarian government and partly due to the high casualty rate
among its leaders.