Battle of Borovo Selo on 2 May 1991 was one of the first armed clashes in the conflict which became known as the Croatian War of Independence. The immediate cause for the confrontation was a failed attempt to replace a Yugoslav flag in the village with a Croatian one. The unauthorized effort by four Croatian policemen resulted in the capture of two by a Croatian Serb militia in the village. To retrieve the captives, Croatian authorities deployed additional police, who drove into an ambush. Twelve Croatian policemen and one Serb paramilitary were killed in the battle before the Yugoslav People's Army (JNA) intervened and stopped the fighting. Croatian independence referendum was called on 19 May 1991 while Serb local authorities called for a boycott of the vote, which was largely followed by Croatian Serbs. On June 25, 1991, at the same day as the Socialist Republic of Croatia declared its withdrawal from Yugoslavia, a self-proclaimed Serbian Autonomous Oblast SAO Eastern Slavonia, Baranja and Western Syrmia was established. In 1992, the oblast joined the breakaway Republic of Serbian Krajina. After the fall of Republic of Serbian Krajina rump Eastern Slavonia, Baranja and Western Syrmia remained as a short-lived Serb parallel entity. After the Erdut Agreement, the territory was reintegrated into Croatia within UN peacekeeping mission UNTAES. On 22 of May 1997 Borovo Municipality was established for a fourth time. It became one of the founding municipalities of a Joint Council of Municipalities.