Noun
(military) The line of battle of one's enemy.
(military, also figuratively, usually in the plural) The boundary of the territory controlled by the enemy.
Source: en.wiktionary.orgAt 12:45, Victory cut the enemy line between Villeneuve's flagship Bucentaure and Redoutable; she came close to the Bucentaure, firing a devastating raking broadside through her stern which killed and wounded many on her gundecks. Source: Internet
The intention was to split the enemy line and engage in close quarter action, a form of combat in which, Nelson believed, the British fleet would have the advantage. Source: Internet