We're holding his place against all comers.

We must barricade the danger points.

The headquarters of the garrison will be in the hall, where a scout must be always on duty.

You've all got whistles?
Well, if there's an attempt on the verandah door the picket will whistle once, if at the back door twice, if anywhere else three times, and it's everybody's duty, except the picket who whistles, to get back to the hall for orders." "That's so," assented Dougal.
"If the enemy forces an entrance we must overpower him.

Any means you like.