3-55. In many large scale incidents, state National Guard and federal military forces operate in overlapping operational areas under separate chains of command. A parallel command structure enhances unity of effort, but its success depends on continuous coordination between all of its components. Within a parallel command structure, there is no single force commander and therefore no unity of command in the military sense. Both the federal and state commanders retain control of their respective forces. Decisions regarding an operation require the collective effort of all participating leaders: state and federal civil authorities, and state and federal military leaders. Leaders collaborate as partners, based on the NIMS and NRF, to develop common goals, unify their efforts, and accomplish the mission. (Figure 3-5, on page 3-12, illustrates a parallel command structure.)