general headquarters 
noun [treated as singular or plural]
The headquarters of a military commander: the leader announced that the general headquarters was being transferred...
- Placing military advisers with the rank of major or lieutenant colonel at the Colombian Army's general headquarters is the next step.
- In the fall of 1941, he took his corps to the general headquarters maneuvers in the Carolinas, which proved a crucial testing ground for the rapidly approaching war.
- As soon as I arrived in Canton by plane, I visited general headquarters, but unfortunately the Lieutenant General was out.