Learning history in school I was always told regarding the blitzkrieg attack to Britain, Germany pushed in through Belgium they defended themselves and held them off long enough for Britain to fortify and retreat. Did such a small country really play such a big part in this war.
Well what you described is basically it.
The Blitzkrieg tactic tried to get through the Ardennes (the Bulge) and go right sharply to reach the sea. This was done to make sure Americans and Brits could not land in the beaches and go freely to the front as they did in 1914 and 1917.
The Belgian army was rather small and not extremely well trained because of the recession before it. It was not able to delay the Germans through the Ardennes much, but was able to buy enough time to get the info to the French (who, thanks to their "old" army kinda f*cked things up). Regarding the capture of the rest of Belgium, the army managed to slow down the German advance enough for the so-called Dunkirk phenomenon to happen (although that was also a fault of Hitler). However army personnel was also saved from the beaches of Oostende, Nieuwpoort and De Panne (all Belgian).
I don't know the exact number, but the capture of the entire country of Belgium took about 10 days (10th of may to the 20th) which is massive if you consider the Dutch (with almost twice the size) capitulated in 3 days.