 Late 1991 saw the fiercest fighting of the Croatian War of Independence, culminating in the Siege of Dubrovnik and the Battle of Vukovar.A campaign of ethnic cleansing then began in the RSK, and most non-Serbs were expelled.In January 1992, an agreement to implement the peace plan negotiated by UN special envoy Cyrus Vance was signed by Croatia, the JNA and the UN.