This is a tentative history of smoke generator operations in the Mediterranean and European theaters of operation in World War II. Contents include information about weapons, smoke generator units, employment, large area screening operation in MTO, smoke generator operations in Normandy, operations with the Third Army, Ninth Army smoke generator operations, operations with the First and Seventh armies, and materiel problems. The first chapter of the present study briefly sets forth the military need for large area screens in rear areas and the consequent development of smoke weapons and equipment as part of the defense against the bombing of friendly ports. Chapter II is concerned with the activation of, and demand for, smoke generator units. Chapter III traces the development of the principles and techniques of tactical employment. Chapter IV relates the activities of the various smoke generator units in MTO and discusses the shift of emphasis from screening rear areas to making smoke in forward areas. Chapter V tells of the plans for laying large area screens over the beaches of Normandy at the time of the invasion. Chapters VI through IX set forth in some detail a number of specific forward area screening operations of the smoke generator units with the four US Armies in ETO. Of these, the operations with the Third and Seventh Armies are of special significance. The final chapter is an account of the materiel problems encountered by the chemical smoke generator units in MTO and ETO.