At the outbreak of World War II on 1 September 1939, the Polish Air Force still had 30 PZL P.7a fighters in combat units. A further 40 were in air schools, 35 in reserve or repairs – a total of 106 available aircraft. The P.7as were used in three squadrons, each with 10 aircraft. The 123rd Squadron was in the Pursuit Brigade, deployed around Warsaw, the 151st and the 162nd Squadrons were assigned to land Armies. Despite being obsolete, they took part in the defence of the country during the German invasion of Poland. Apart from combat units, at least 18 P.7a fighters were mobilized in units improvised at air bases in Dęblin and Ułęż.