The United States appointed Eisenhower to lead the invasion, who later planned with the help from British General Bernard Montgomery, an attack known as Operation Overlord. The British developed an intelligence community, which is known as "Ultra", ultra was a British "intelligence coup of the first magnitude." (Ambrose, 262) Every message that was picked up by Ultra was decoded and translated, the Germans didn't have any knowledge of this occurring. The British knew where the Germans were located, Ultra for the purpose of Operation Overlord, provided the Allies information on "enemy order of battle." (Ambrose, 269) The British kept Ultra a secret for a long period of time that Germans still believed their codes were still secure. …show more content…
They gave the Germans very little information, that didn't give the British away but, made them believe their spies had access to important British military initiatives. The Double-Cross System was a big part of the success of Operation Overlord, with the double agents it provided information that led the victory of D-Day