Salient
From Wikipedia:
A salient, also known as a bulge, is a battlefield feature that projects into enemy territory. The salient is surrounded by the enemy on multiple sides, making the troops occupying the salient vulnerable.
Geometry dictates that salients require a longer line of defense than a straight line, and they are exposed on three sides.
Why I Looked It Up
The word kept coming up in The First World War. Specifically, it discussed the “Ypres Salient,” which was a bulge in the front line around the city of Ypres.
The Allied trenches would have gone directly through the middle of Ypres, but they rounded east in order to encapsulate the city. It was the site of several battles.
Postscript
Added on
So, it turns out this is a general word as well:
A pronounced feature or part; a highlight.
Anything can be “salient.” For instance, the “salient points” of a document are, effectively, the highlights.
On a NY Times article about an intelligence leak:
And it’s the immediate salience of the intelligence that most worries White House and Pentagon officials.
I’m not sure about the “immediate” qualifier here, honestly. If intelligence was “salient,” it would be prominent. Not sure how much immediacy matters.