enemy line

noun2

1. •
   The line of battle of one's enemy.

   • Once the two fleets had met, it was then likely, if not inevitable, that only some of the attacking fleet would make it through the enemy line. — 2008
2. •
   [usually plural] The boundary of the territory controlled by the enemy.

   • The aviation service can, in two hours, go 100 miles back of enemy lines and return, bringing important information. — 1917