《旧唐书·列传·卷一百零四》
因吴元济向北进犯，京郊多警报，防御之兵尽去伊阙驻守。
因吴元济北犯，郊畿多警，防御兵尽戍伊阙。
When Wu Yuanji invaded the north, there were many alerts in the suburbs of Beijing, and all the defense soldiers went to the Yi Valley for garrison duty.