After losing several in this way, he pulled the remainder back to form a defensive perimeter.

They were called back to their seats, and those who had formed the defensive perimeter reboarded the other helicopter.

To protect the inhabitants, the brigade's three battalions established a defensive perimeter around the outskirts of the town.

Settling into static positions atop the 1500 ft hill, they established a defensive perimeter around the poorly-covered and -concealed hilltop to establish their observation post.

The newly hatched godling quickly began creating a defensive perimeter of traps and restoring the caverns.