在平定安(an)史(shi)之亂(luan)得過程中,為(wei)求得暫時茍安(an),唐代宗措(cuo)置失當(dang),“瓜(gua)分河北地,付授(shou)叛(pan)將”,使(shi)(shi)安(an)史(shi)降將搖身一變,成了由中央任命的(de)節度使(shi)(shi),保存(cun)了相(xiang)當(dang)大的(de)離心力。在平叛(pan)過程中,朝廷還對內地掌握兵(bing)權的(de)刺史(shi)多加節度使(shi)(shi)稱號(hao),造成了亂(luan)后“方鎮相(xiang)望于內地,大者連(lian)州十(shi)余,小者猶兼三四”的(de)藩(fan)鎮割據的(de)嚴重局面。
唐德(de)(de)宗(zong)(zong)即位后(hou),力圖削藩。建中二年(781)正(zheng)(zheng)月(yue),成德(de)(de)節度(du)使(shi)李(li)(li)(li)(li)寶(bao)臣死,子李(li)(li)(li)(li)惟岳向朝(chao)廷(ting)請(qing)求襲(xi)其(qi)父位,魏博節度(du)使(shi)田悅亦代為(wei)之(zhi)請(qing)。德(de)(de)宗(zong)(zong)堅決(jue)拒絕。李(li)(li)(li)(li)、田遂聯合淄青節度(du)使(shi)李(li)(li)(li)(li)正(zheng)(zheng)己(ji),山南東(dong)道(dao)節度(du)使(shi)梁(liang)(liang)崇義(yi)等起兵反唐。七月(yue)李(li)(li)(li)(li)正(zheng)(zheng)己(ji)死,八月(yue)子李(li)(li)(li)(li)納(na)亦請(qing)襲(xi)父位,德(de)(de)宗(zong)(zong)不允,李(li)(li)(li)(li)納(na)遂反。戰事日益擴大(da)。建中四年正(zheng)(zheng)月(yue),割據(ju)淮西(xi)(今(jin)(jin)河南汝(ru)南)的節度(du)使(shi)李(li)(li)(li)(li)希烈叛,攻襄城(今(jin)(jin)屬河南)。德(de)(de)宗(zong)(zong)派哥舒曜討伐,未果。德(de)(de)宗(zong)(zong)又派涇原(yuan)兵去解圍。時(shi)(shi)涇原(yuan)節度(du)使(shi)朱(zhu)泚(ci)(ci)(ci)因其(qi)弟朱(zhu)滔謀反而被軟禁于京城。涇原(yuan)兵路過長(chang)安(an)時(shi)(shi),因賞賜不周,挾持節度(du)使(shi)姚令言嘩變。德(de)(de)宗(zong)(zong)逃(tao)往奉天。叛軍推舉朱(zhu)泚(ci)(ci)(ci)為(wei)首領,史稱(cheng)(cheng)(cheng)涇原(yuan)之(zhi)變。朱(zhu)泚(ci)(ci)(ci)率(lv)軍攻奉天,未下(xia)。此時(shi)(shi)朝(chao)廷(ting)援(yuan)兵已逼長(chang)安(an),朱(zhu)泚(ci)(ci)(ci)退守(shou)長(chang)安(an)。不久唐將領李(li)(li)(li)(li)懷光(guang)與朱(zhu)泚(ci)(ci)(ci)聯合。德(de)(de)宗(zong)(zong)被迫(po)又奔梁(liang)(liang)州(今(jin)(jin)陜西(xi)漢中)。興元元年(784)五月(yue),唐將領李(li)(li)(li)(li)晟等攻克(ke)長(chang)安(an),德(de)(de)宗(zong)(zong)于七月(yue)返(fan)回。朱(zhu)泚(ci)(ci)(ci)被部下(xia)所殺。朱(zhu)滔病死。李(li)(li)(li)(li)懷光(guang)兵敗自縊。因在(zai)這次戰爭中,有四人稱(cheng)(cheng)(cheng)王(wang)(wang),兩人稱(cheng)(cheng)(cheng)帝(di),即朱(zhu)滔稱(cheng)(cheng)(cheng)冀王(wang)(wang),王(wang)(wang)武俊稱(cheng)(cheng)(cheng)趙王(wang)(wang),田悅稱(cheng)(cheng)(cheng)魏王(wang)(wang),李(li)(li)(li)(li)納(na)稱(cheng)(cheng)(cheng)齊王(wang)(wang),朱(zhu)泚(ci)(ci)(ci)稱(cheng)(cheng)(cheng)秦帝(di),李(li)(li)(li)(li)希烈稱(cheng)(cheng)(cheng)楚帝(di),故又稱(cheng)(cheng)(cheng)二帝(di)四王(wang)(wang)之(zhi)亂。