In an attempt to split the US First and Third Armies at Avranches, Hitler ordered all panzer units in Normandy to conduct an attack west to the sea. The advance fell short due to the heroics of the US 30th Infantry Division and US and UK tactical air strikes defending Hill 314 just east of the town of Mortain.
IX TAC had the mission of keeping the Luftwaffe out of the ground battle. You will attack the largest German air base supporting the German ground forces.