The 
second Schweinfurt raid,
[10] also called 
Black Thursday, was a 
World War II air battle that took place on 14 October 1943, over 
Nazi Germany between forces of the United States 
8th Air Force and German 
Luftwaffe fighter arm (
Jagdwaffe). The American bombers conducted a 
strategic bombing raid on 
ball bearing factories to reduce production of these vital parts for all manner of war machines. This was the second attack on the factories at 
Schweinfurt. American wartime intelligence claimed the first 
Schweinfurt–Regensburg mission in August had reduced bearing production by 34 percent but had cost many bombers. A planned follow-up raid had to be postponed to rebuild American forces.