I Have Never Seen a Game Like This (10/13/1939) by Jack Patton

The Maginot Line is a strong of concrete fortifications, obstacles and weapon installations built by France in the 1930s to deter invasion by Germany and force them to move around the fortifications. The Siegfried Line, known in German as the Westwall, was a German defensive line built during the 1930s opposite the French Maginot Line. Despite France’s declaration of war on Germany (September 3, 1939) after Germany had invaded Poland three days earlier, there was no major combat at the Siegfried Line except for a minor offensive by the French. Instead, both sides remained stuck in the so-called "Phoney War" (September 1939 through April 1940), where neither side attacked the other and both stayed in their safe positions. The World War II German invasion plan of France for May 1940, following its capture of Norway (ending the phoney war) was designed to deal with the line. A decoy force sat opposite the line while a second Army Group cut through the Low Countries of Belgium and the Netherlands, as well as through the Ardennes Forest, which lay north of the main French defenses. Thus the Germans were able to avoid a direct assault on the Maginot Line by violating the neutrality of Belgium, Luxembourg and the Netherlands.