Bahrain participated in the Second World War on the Allied side, joining on 10 September 1939. On 19 October 1940, four Italian SM.82s bombers bombed Bahrain alongside Dhahran oilfields in Saudi Arabia, targeting Allied-operated oil refineries. Although minimal damage was caused in both locations, the attack forced the Allies to upgrade Bahrain's defences, an action which further stretched Allied military resources.