 Formal establishment of these forces was preceded by the first armed clashes in the country as the Bosnian Serbs set up barricades in Sarajevo and elsewhere on 1 March and the situation rapidly escalated.Bosnian Serb artillery began shelling Bosanski Brod by the end of March, and Sarajevo was first shelled on 4 April.By the end of 1992, the VRS held 70% of Bosnia and Herzegovina, following a large-scale campaign of conquest and ethnic cleansing backed by military and financial support from the Federal Republic of Yugoslavia.