German options if Belgium is avoided

French fortress-building after the Franco-Prussian War left any German plan that avoided Belgium facing strong defenses and predictable French offensives. Germany could let the French army advance and then encircle it, but that would expose the industrial heartland and run against the army's offensive habits. Switzerland was an even worse substitute because armed neutrality, mountain passes, mines, and avalanche terrain demanded an extreme local force advantage. A seaborne move around Belgium therefore becomes the remaining option. This turns a land-campaign problem into a naval and logistical one.