The primarily Canadian landing force at Juno beach split between the Mike and Nan Sectors on either side of Courseulles-sur-Mer. Landings were postponed by ten minutes to allow the rising tide to cover reefs that were hampering the landing craft, however this also alerted German defences to the imminent attack. Armoured units were subsequently delayed from supporting the first wave of infantry, who were pinned down on the beach by machine gun fire, resulting in an almost 50 per cent fatality rate for the initial infantry attack. Many vehicles moving up the beaches were also destroyed by mines due to the minimal effectiveness of the minesweepers. As infantry moved towards the defensive installations, it became clear that artillery bombardment had been largely ineffective. Particularly heavy defensive fire came from positions in Bernières in front of Nan sector, however once the beach defences were breached, Allied forces were able to push quickly inland.