Sentence:  The German intelligence staffs again agreed that there was no immediate threat to the Seventh Army, and that the westward advance by the Fifth Panzer Army would necessarily force the Americans to strengthen the <WSD>battle line</WSD> there and prohibit any thrust into the deep southern flank. 
Meaning of the word marked with <WSD> tags:  The notional line on either side of which opposing forces are arrayed, and at which they meet in battle; a fortified line, short of the line where battle is expected, and behind which forces are arrayed; a forward line of infantry or other force, prepared for battle.