Final answer:
High-ranking officials like the Chair of the Joint Chiefs of Staff and the national security advisor provide leadership in their direct chain of command and for the entire unit, advising the president and coordinating military or foreign policy efforts.
Step-by-step explanation:
Personnel who provide leadership both within their direct chain of command and for the entire unit are typically high-ranking officials who hold crucial positions within a nation's military or governmental structure. For instance, in the United States, the Chair of the Joint Chiefs of Staff plays a pivotal role as a top military advisor to the president and embodies this dual-command leadership role by offering guidance both to the president and within the military hierarchy. Similarly, the national security advisor provides leadership by heading the National Security Council, advising the president on foreign policy matters, and coordinating efforts across multiple foreign policy agencies.