The wartime career of 57 Squadron began within weeks of the start of hostilities, when, as part of the Advanced Air Striking Force, it found itself in northern France at the end of September 1939 and forming 70 Wing with 18 Squadron. Equipped with the Blenheim Mk I the squadron launched its first reconnaissance sorties over north-western Germany on the 12th of October, from which the commanding officer failed to return. The remainder of the year saw the squadron continue in a reconnaissance role with occasional losses to enemy action. The harsh winter restricted operations until March, when the Mk IV Blenheim replaced the Mk I. When German forces invaded the Low Countries on the 10th of May, the Fairey Battle and Blenheim squadrons of the AASF were pitched into an unequal fight against German fighters and entrenched flak positions and were effectively knocked out of the conflict.
Withdrawn to England, 57 Squadron joined 3 Group and re-equipped with Wellingtons to take its place in Bomber Command's front line until a posting to 5 Group in September 1942 brought a new phase of operations on Lancasters. From that point until the end of the war, 57 Squadron participated in all of Bomber Command's campaigns against the Ruhr, Hamburg, Berlin, railways, oil, V-Weapons, tactical support of the ground forces, canals and a second Ruhr offensive in late 1944. It also contributed its C Flight as the nucleus of the newly forming 617 Squadron in preparation for the "Dambusters" raid.
It was not a lucky squadron and ended the war with the highest percentage loss rate in the Command. Its record of service bears comparison with any in the Command, and its final wartime home, East Kirkby, now stands in tribute to its crews and those of 630 Squadron.