OTOH, that's also where there were the most troops facing the Germans - neutral in addition to French, plus British expeditionary forces within a short hop across the Channel... It was the specific nature of defenses and obstacles, rather than their general quantity, that mattered the most.
Are border defenses of importance in Trek? We have seldom seen anybody intercepted at
a border, or even observed crossing it. And the most devastating defenses have been mounted deep insystem, with the possible exception of the battle to retake Bajor from the Dominion (because it took a bit of warping after the battle to get to DS9).