The US Air Force Historical Division wrote a report in response to the international concern about the bombing that remained classified until December 1978. It said that there were 110 factories and 50,000 workers in the city supporting the German war effort at the time of the raid. According to the report, there were aircraft components factories; a poison gas factory (Chemische Fabrik Goye and Company); an anti-aircraft and field gun factory (Lehman); an optical goods factory (Zeiss Ikon AG); and factories producing electrical and X-ray apparatus ( AG); gears and differentials (Saxoniswerke); and electric gauges (Gebrüder Bassler). It also said there were barracks, hutted camps, and a munitions storage depot.