Belgium is located between Germany and France so Belgium and the rest of the world are upset because the Germans disregarded Belgium's rights and violated the law.
Neither Belgium nor France nor Britain were surprised that Nazi Germany attacked and violated neutrality without an official declaration of war. He did this a long time ago with Poland, Denmark en Norway.
That is why the cream of the French and British troops flew to Belgium for help, and General Eric von Manstein fell into the (then) trap as the German Panzer Division advanced through Ardennes and Franco. The British Army
