General Halder (German High Command chief of staff) responds to Hitler's Directive for an invasion of France and presents his plan. “Case yellow” is a pedestrian drive through Belgium to the North Sea (based on WWI’s Schleiffen plan) designed to separate the British Expeditionary Force from the French army. Halder is possibly trying to deter Hitler from attacking at all and he estimates this will cost hundreds of thousands of German casualties and not deliver a full invasion of France until 1942. This is not the quick mechanized thrust into France that Hitler wants, with the element of surprise limiting German casualties. Hitler is not pleased; however, his impatience will quickly lead him to endorse this plan and order its execution. Generals von Rundstedt and von Manstein soon get wind of this and devise their own plan.