Redoubt
Definition: a small, defensive fortification
Why I Looked It Up
From Kingmakers:
More unusually, accompanied by his father, he also viewed deranged inmates in a Damascus asylum and sipped tea with Druze sheiks in their Lebanese redoubt.
Update
Added on
In the spy novel Eurostorm:
He had no idea what was unfolding up in that mountain redoubt, but he was damned well going to find out.