This paper describes the design and operation of the microgrid installed for the US Department of Defense at Fort Sill, Oklahoma. The microgrid is composed of two natural gas generators, a battery energy storage inverter, renewables, and a static switch. Design considerations for this retrofit application with a high penetration of dynamic loads are given. The integration of the energy storage inverter with a commercial isochronous generator control system is described. A comparison of droop control vs. isochronous control is provided, and the benefits of using an existing isochronous generator control system for microgrid applications are described. System performance is validated by simulation results.