 On 10 September 1939 it was engaged in attacks on troop concentrations north of Praha, and bombed Polish Army forces east of Brześć Litewski on 15 September as the Battle of Brześć Litewski raged.The rest of the unit did not participate during the campaign.I./KG 54 was withdrawn on 20 September and put on standby in western Germany, in case of Western Allied attacks, which aside from a token advance into German territory, did not materialise.