The actual headquarter and seat of the Mantellian Commonwealth is not on Ord Mantell, not even in the system. It was just the planets orbit the treaty was signed in, on the current flagship "Caesar". But the base of the Commonwealth is the space station 'Mare Nostrum', a large station in open space between Ord Mantell and Qiilura.
The majority of the Commonwealth Navy is often docked here, as long as they are not deployed. There are plans for new stations to divide the seats of authority, but they just went into development. The high command of the fleet based here is responsible for all matters regarding the fleet, operation centre, admiral staff as well as recruitment or rather introduction.
As no Lord High Commandant has been named yet from among the Commandants, the role is fulfilled by the de jure leader of the Mantellian Commonwealth - the Lord Executor. Luckily the leaderships of the Commonwealth are still on the same station and therefore the offices are close.
Todays duties for the Lord Executor are many, but one has to be highlighted. A new captain is to be introduced for the new ship which was recently commissioned. A new captain for the Nova Thorn. Waiting in one of the offices at the admirality, close to the operation centre, Vespasian waits for the Captain, who got visitor and security clearances for the areas necessary.