[moccachino]

Thanks for the Wikipedia link. From the results of this exercise it seems it really was necessary, in order to avoid the same catastrophes on D-day itself. However the operation did alert the Nazis that something was up, and they apparently did reinforce the landing sites in preparation for an assault.

As a side not since this is HN: The article summary box lists Nazi Germany as a party to the exercise with all of the E-boats, presumably due to article quality control requirements in the Wikipedia system.