[Turhan's Bey Company]

A single roll? Yeah, that's the kind of thing you really, really should play out, but if you absolutely must do it in a single roll, I'd go with Strategy. A military coup is ultimately a surprise attack, hitting your enemy in carefully chosen locations before he can shoot back at you.

That said, I'd go with at least two or three rolls: Administration or Politics to pick the right targets, because while it's a military action its in pursuit of targets which are the political leadership and administrative machinery of a nation; Strategy for proper planning and execution of the action; and Leadership to keep the whole dubious enterprise together under trying circumstances. A failure on one of those means you've picked a wrong target or failed to execute properly, so your enemies still have some power and can fight back. Failure on two or three means the whole enterprise has collapsed and it's best to flee the country.