On 14 June 1944, 617 squadron made a daylight attack upon the E boat pens at Le Havre. The pens protected fifteen E boats, which posed a threat to the invasion fleet. Attacking the pens with Tallboys, the roof was caved in, and all but one of the E boats were damaged beyond use. In addition, 617 attacked the German ships in Le Havre by dropping Tallboys into the waters of the harbour. The explosions were so strong that ten ships were blown straight out of the water and onto the quayside. Commented Cheshire, "Barnes Wallis had a big bomb."