sentences:  In 1922 after gaining the approval by a plebiscite, the government began trying and imprisoning leaders of opposition parties for their roles in previous wars.In the face of repression, several parties decided that the overthrow of the government was a necessity to their survival.Based in the Macedonian region of Bulgaria the nationalist and revolutionary Internal Macedonian Revolutionary Organization carried out attacks against Greece and the Kingdom of Yugoslavia in attempt to free the Bulgarian lands under Greek and Yugoslav rule.