He didn't. The Schlieffen Plan was always more than just a war plan to invade France through Belgium, since it's main purpose was to avoid a two-front war. Schlieffen planned eliminate France before its slower-mobilizing Russian ally was ready, and then move the German armies on the German railways to the Eastern Front to face the now-mobilized Russians. In 1940, Hitler had no need for this because of the 1939 Molotov -Ribbentrop Pact that had temporarily secured Nazi-Soviet non-aggression.

So even if you take the failure to defeat France to mean that Schlieffen plan was an irredeemable failure, which ASesz shows is not entirely correct, one advantage Hitler had over Moltke was not being in a rush to secure his Eastern Front.

To say the hammer through Belgium "failed" in WW1 is a bit incorrect.

When the Germans moved on the western front, they realized an assault along the entire front was viable. The french took heavy casualties due to outdated tactics and lack of heavy field guns. As the French/British fell back, the "hammer" that was meant to drop through Belgium was no longer able to push behind the lines as the allies had fallen back, basically to Paris. At this point, the french rallied along with the British and made a very lucky/strategic offensive that smashed the German North. The allied armies along with colonial reinforcements (Canada, India..) slowly drove the Germans back (grueling trench war).

In preparation for WW2, the french built an enormous line of defenses along their border with Germany - the "Maginot Line". The French basically thought to hold the Germans here and therefore concentrated their static defense here. Once again, Belgium was the easiest way in for the Germans. Along with the new German tanks, Hitler believed he could smash though the North with unprecedented speed and bypass the line entirely.

Well it's kind of the only plan if Germany wants to take out France. Here's a map for reference. Consider the options:

• Go south into Switzerland and attack along the Swiss-French border. Firstly, Switzerland is neutral...as always. Secondly, the Swiss Alps are not the best place to roll tanks through. Thirdly...you're so far from the capital...a quick knock out punch would be out of the question.

• Germany could go down through Austria, to Northern Italy and attack along the French-Italian border, but again...you're far from Paris, so going from the South is not viable.

• Attack France along the French-German border. The Maginot defensive line was still there. You do anything to try and avoid fortified enemy positions...trenches, bunkers, dug in artillery, barbed wire etc.

• Sail a navy into the Channel, separate the UK from France and land in France's northern beaches. 1) England ruled the waves. 2) Beach landings are complicated and require A TON OF PLANNING(see D-Day; also why Hitler was reluctant to land in England after taking out France).

So really the only plan was the old plan...knock out Belgium and the Netherlands, then take out Paris and voila! Now that the Germans had perfected the Blitzkrieg(see Poland), they had the means to see this plan through.