The Grand Slam was a 22,000 lb earthquake bomb used by RAF Bomber Command against strategic targets during the Second World War.
It was a scaled up version of the Tallboy bomb and closer to the original size that the bomb inventor Barnes Wallis had envisaged when he first developed his earthquake bomb idea.
Bielefeld, 14 March 1945
The No. 617 Squadron RAF Avro Lancaster of Squadron Leader CC Calder dropped the first Grand Slam bomb from 4900 m /16,000 ft on the Bielefeld viaduct. More than 100 yards of the Bielefeld viaduct collapsed through the earth quake bomb effect of the Grand Slam and Tallboy bombs of No. 617 Squadron. No aircraft were lost.
Arnsberg, 19 March 1945
37 Lancasters of No. 5 Group RAF attacked the railway viaduct at Arnsberg and the bridge at Vlotho, near Minden. The attack at Arnsberg by No. 617 Squadron RAF using 6 Grand Slams blew a 12 m / 40-foot gap in the viaduct. No. 9 Squadron RAF’s attack at Vlotho was not successful.
