《资治通鉴·唐纪·唐纪五十六》
讨伐王承宗的河东、幽州、义武、横海、魏博、昭义六藩镇，拥有兵马十多万人，辗转数千里，既设有统领各军的主帅，又相隔遥远，约定的日期难以统一，因此历时两年，毫无建树，运输物资的路程长达千里，死去的牛和驴有十分之四五。
六镇讨王承宗者兵十馀万，回环数千里，既无统帅，又相去运，期约难壹，由是历二年无功，千里馈运，牛驴死者什四五。
To conquer Wang Chengzong, six Garrison areas in Hedong, Youzhou, Yiwei, Henghai, Weibo and Zhaoyi, with more than one hundred thousands soldiers and horses, had marched thousands of miles. There was not only a commander to lead various armies, but also they were far apart. It was hard to unify the agreed date, so it took two years but achieved nothing. The routes to transport supplies were thousands of miles long, four or five out of ten cattle and donkeys died.