In the early modern era they were used to block possible lines of advance.

And it meant the end of a possible line of defense.

Simply as a mental exercise, without any assertion that it is true, let me indicate a possible line of thought.

You watch the top people in every possible line of endeavor.

Naturally, you would take care to stay clear of any possible line of fire.

It remains a possible front line in any renewed fighting.

It is vital to avoid camping in their possible line of fall.

It even indicated the only possible line of treatment to be taken.

I would have gotten up but Curran's hand kept me below the possible line of fire.

Many homes across the street and in the possible line of fire were evacuated.