Croatia has been at war since 1991 when it ceded from Yugoslavia. Cessation prompted a crackdown by Belgrade and an uprising by the Serbian minority. During the war of independence millions of mines were planted and the main cities were bombed. Western Slavonia and the Krajina were under the control of Serb forces loyal to Belgrade until April 1995 when Croatian HVO forces retook Western Slavonia. Zagreb was shelled in retaliation. In August 1995 Croatian forces swept across the border of Bosnia and Herzegovina to pursue the fleeing Serbs, and to dislodge Serb forces near Croatian territory. Croatian officials came out of the Dayton Peace Accords of November 1995 with an agreement by Belgrade that Serbs vacate the disputed and oil-rich Slavonia region. Eastern Slavonia was returned to Croatian control on Jan.15, 1998.