This illustrated study charts the development and combat history of the Dornier Do 217 Units, the Luftwaffe's workhorse bomber during World War II. The Dornier Do 217 had a much larger bomb load capacity and had considerably greater range than the Do 17, which it replaced in frontline service from early 1941. Although initially used simply as a bomber, later variants were developed that allowed the Do 217 to undertake dive-bombing and maritime strike roles. In order to perform the latter mission, the Do 217 was modified to launch glide bombs - units employing these pioneering weapons enjoyed considerable success in the Mediterranean from the autumn of 1943. Indeed, during the course of these operations the Do 217 became the first aircraft in military aviation history to deploy a precision-guided bomb in combat in the form of the 'Fritz X' radio-guided, free-fall weapon, which sank the Italian battleship Roma shortly after Italy capitulated in September 1943. The Do 217 served on all fronts and also performed tactical operations, either direct ground assault or anti-shipping strikes during the Battles of the Atlantic and Normandy. This versatile aircraft was also converted to become a nightfighter, seeing considerable action in the Defense of the Reich until war's end. This illustrated study explores the design, development, and the many different deployments of the Do 217, charting its role, as strategic bomber, reconnaissance aircraft, and torpedo-bomber, among others.