Moving military troops, which is critical to tactical success, depends on providing large quantities of fuel. We used simulation to model and analyze the Turkish army's fuel-supply system that consists of sea-going tankers, tank fields, pipelines, and depots. We measured performance of the existing and proposed systems under various scenarios. We developed a simulation optimization model based on a genetic algorithm (GA) to optimize system performance. Based on the results of extensive simulation experiments, we proposed a number of changes. We recommended that the army should open the existing fuel-supply system and that it establish commercial use in peacetime to obtain additional operating revenue. New trigger levels (or fuel-replenishment policies) for wartime allow the fuel-supply system to survive much longer even in the most severe war conditions. These specific recommendations are being considered by the top army officials to obtain benefits worth millions of dollars.