Boulton Paul Defiant.The purpose of this volume is to provide a comprehensive detailed study of the operational and combat operations of the RAF's Boulton Paul Defiant MK.I turret armed fighter aircraft during the hectic air battles of mid and late May 1940, the latter period of which the Defiant was heavily involved in operations against Luftwaffe fighters and bombers attacking the British Expeditionary Force evacuation operations on the channel coast, particularly around Dunkirk. It also covers the Defiants operations in the air battles of July and August at the height of the Battle of Britain, when 264 Squadron and 141 Squadron flew day and night operations, suffering severe losses. A brief description of the genesis and development of the Defiant MK.I fighter is laid down, but the volume is not designed to be a comprehensive monograph on that subject. A brief description of the Defiants main fighter adversary, the German Me.109E, is also provided. The volume is copiously supported by a wealth of operational documents including Squadron Narratives, Group Intelligence Combat Reports, Squadron operational Records and pilot Personal Combat Reports, many of which are reproduced verbatim. Operational documents have been tied up against German reports whenever possible which naturally results in areas of disputed figures, particularly with regards to numbers of German aircraft shot down.