Answer: The German attack on France in the 1940s was a success. Germany took over France in that attack, even using their own trench guns against them.
Explanation: France made a mistake after WWI by spending a tone of money on building a massive trench system around France in case of a 2nd world war. However, trench warfare was deemed to be useless in WWII, so useless that the Germans used the machine guns inside of those trenches against the French.