chief of staff 
noun
The senior staff officer of a service, command, or formation.The course could expand its current target audience of brigadier and major generals to include former brigade commanders, division chiefs of staff, corps G3s, and other senior colonels....
- The ministry of defense provides administrative and operational control over the three services through their respective chiefs of staff.
- Consisting of the prime minister, the service ministers, the chiefs of staff, and the foreign minister, the Council proved somewhat more effective.