Franz Halder — German Soldier born on June 30, 1884, died on April 02, 1972

Franz Halder was a German general and the chief of the OKH General Staff from 1938 until September 1942, when he was dismissed after frequent disagreements with Adolf Hitler. Until December 1941 Halder's military position corresponded to the old Chief of the General Staff position, which during World War One was the highest military office in the German Imperial Army. Halder's diary during his time as chief of OKH General Staff has been a source for authors that have written about such subjects as Adolf Hitler, the Second World War and the NSDAP. In William Shirer's The Rise and Fall of the Third Reich, Halder's diary is cited hundreds of times... (wikipedia)

The left-wing, which consists of armoured and motorized forces and has no enemy in front of it, will be stopped dead in its tracks upon direct order from the Fuhrer.
The reason is that a military defeat of Britain will bring about the disintegration of the British Empire. This would not be of any benefit to Germany.
The finishing off of the encircled enemy army is to be left to the Luftwaffe.