Another attack by the 7th Armoured Division and other offensive operations were abandoned when a severe storm descended on the English Channel on 19 June.[14] The storm lasted for three days and further delayed the Allied build-up.[15] Most of the convoys of landing craft and ships already at sea were driven back to ports in Britain; towed barges and other loads (including 2.5 miles (4.0 km) of floating roadways for the Mulberry harbours) were lost and 800 craft were left stranded on Normandy beaches until the spring tides in July.[16]