The Americans , assigned to land at Utah and Omaha , was to cut off the Cotentin Peninsula and capture the port facilities at Cherbourg . The British at Sword and Gold , and the Canadians at Juno , was to capture Caen and form a front line from Caumont @-@ l 'Éventé to the south @-@ east of Caen to protect the American flank , while establishing airfields near Caen . Possession of Caen and its surroundings would provide a suitable staging area for a push south to capture the town of Falaise . A secure lodgement would be established and an attempt made to hold all territory north of the Avranches @-@ Falaise line during the first three weeks . The Allied armies would then swing left to advance towards the River Seine . Montgomery envisaged a ninety @-@ day battle , ending when all the forces reached the Seine .