唐朝滅亡之后,沙陀人李克用建立后唐。到末帝李從珂繼位時,大將石敬瑭成為河東節度使。后來李從珂對石(shi)(shi)敬(jing)瑭(tang)(tang)起疑心,石(shi)(shi)敬(jing)瑭(tang)(tang)也暗謀自(zi)保。李從珂后(hou)來改授(shou)石(shi)(shi)敬(jing)瑭(tang)(tang)為(wei)(wei)天平軍(jun)節度(du)使,并(bing)降(jiang)旨催促(cu)赴任(ren),石(shi)(shi)敬(jing)瑭(tang)(tang)便叛變。后(hou)唐(tang)于是派兵討(tao)伐,石(shi)(shi)敬(jing)瑭(tang)(tang)被(bei)圍,向(xiang)契(qi)(qi)(qi)丹(dan)(dan)(dan)皇(huang)帝(di)耶律德(de)光求援。9月(yue)契(qi)(qi)(qi)丹(dan)(dan)(dan)軍(jun)南(nan)下(xia),擊敗唐(tang)軍(jun)。石(shi)(shi)敬(jing)瑭(tang)(tang)在(zai)(zai)十一月(yue)受契(qi)(qi)(qi)丹(dan)(dan)(dan)帝(di)冊封為(wei)(wei)大晉(jin)皇(huang)帝(di),認契(qi)(qi)(qi)丹(dan)(dan)(dan)主耶律德(de)光為(wei)(wei)父,稱(cheng)父皇(huang)帝(di),自(zi)稱(cheng)兒(er)皇(huang)帝(di),然后(hou)向(xiang)后(hou)唐(tang)都城(cheng)洛陽(yang)進軍(jun),末帝(di)在(zai)(zai)937年1月(yue)自(zi)殺,后(hou)唐(tang)滅(mie)亡。石(shi)(shi)敬(jing)瑭(tang)(tang)滅(mie)后(hou)唐(tang)后(hou),建立后(hou)晉(jin),并(bing)在(zai)(zai)938年按約定將燕(yan)云十六州獻給契(qi)(qi)(qi)丹(dan)(dan)(dan)。石(shi)(shi)敬(jing)瑭(tang)(tang)在(zai)(zai)位期間對遼國(guo)稱(cheng)臣(chen)。
天福(fu)七年,后(hou)晉出帝石(shi)重貴即位后(hou),拒絕(jue)再向契丹(dan)稱臣,兩國關系惡化。
契丹太宗耶律德光以晉廷負恩為由,舉兵南下。八年,耶律德光在降將楊光遠、趙延壽勸誘下,乘中原饑荒,晉廷國用困竭之機,調集(ji)山(shan)后媯、檀(tan)、云、應(今(jin)北京(jing)延慶、密云、山(shan)西(xi)大(da)同、應縣)等(deng)州(zhou)及盧(lu)龍(治今(jin)北京(jing)市城(cheng)區西(xi)南(nan))兵(bing)(bing),于十二月兵(bing)(bing)分兩路(lu)南(nan)進。東路(lu)以趙(zhao)延壽率(lv)5萬兵(bing)(bing)為(wei)前鋒,太(tai)宗自率(lv)10余萬大(da)軍(jun)殿后,出南(nan)京(jing)(即幽州(zhou),今(jin)北京(jing))趨魏州(zhou)(今(jin)河北大(da)名東北);西(xi)路(lu)由(you)偉王率(lv)云、應諸軍(jun)入雁門關(今(jin)山(shan)西(xi)代(dai)縣西(xi)北)趨太(tai)原,策應東路(lu)主力作戰。
九年正月,東(dong)路(lu)前鋒軍(jun)(jun)攻陷(xian)晉(jin)糧儲重鎮貝州(治(zhi)清河(he),今(jin)(jin)河(he)北清河(he)西(xi)(xi)北),繼占領南樂(le)(今(jin)(jin)屬(shu)河(he)南),太(tai)宗牙(ya)帳設于(yu)元城(今(jin)(jin)河(he)北大名東(dong)北);西(xi)(xi)路(lu)軍(jun)(jun)破代州(今(jin)(jin)山(shan)西(xi)(xi)代縣(xian)),逼近(jin)忻(xin)(xin)州(今(jin)(jin)屑山(shan)西(xi)(xi))。后晉(jin)出帝(di)聞知,先(xian)遣(qian)使致書契(qi)丹,欲(yu)修舊好(hao),遭(zao)拒。遂以黃河(he)為(wei)屏(ping)障,部署防御(yu):命高行周為(wei)北面行營都部署,率軍(jun)(jun)進駐戚(qi)城(今(jin)(jin)河(he)南濮陽(yang)北);遣(qian)張彥澤戍黎陽(yang)(今(jin)(jin)河(he)南浚縣(xian)東(dong)北);出帝(di)親率禁軍(jun)(jun)抵澶州(今(jin)(jin)河(he)南濮陽(yang))指揮(hui)。另以劉(liu)知遠為(wei)幽州道行營招(zhao)討使,抵御(yu)契(qi)丹西(xi)(xi)路(lu)軍(jun)(jun)。及戰,偉(wei)王軍(jun)(jun)攻秀容(rong)(今(jin)(jin)山(shan)西(xi)(xi)忻(xin)(xin)州),被劉(liu)知遠擊敗,逃至鴉鳴谷(今(jin)(jin)山(shan)西(xi)(xi)壽陽(yang)東(dong)南),東(dong)會(hui)契(qi)丹主力(li)。
二月,太宗率軍圍戚城,遣麻答率數萬兵攻博州(今山東聊城東北),搶渡馬家口(今山東聊城東),會晉叛將楊光遠由翼側包抄,鉗擊正(zheng)面晉(jin)軍。晉(jin)廷命何重進、白再榮(rong)、安(an)彥威(wei)等(deng)分守(shou)麻家口(kou)(今(jin)(jin)山(shan)東(dong)(dong)鄄城(cheng)(cheng)東(dong)(dong)北(bei))、楊劉(今(jin)(jin)山(shan)東(dong)(dong)東(dong)(dong)阿東(dong)(dong)北(bei)楊劉鎮)、馬(ma)家口(kou)、河陽(今(jin)(jin)河南孟縣南),加(jia)強諸津要守(shou)備。同時,遣侍(shi)衛馬(ma)軍都指(zhi)揮使李(li)守(shou)貞(zhen)、神武統軍皇甫遇等(deng)率兵萬(wan)余,沿河水陸并進,疾趨馬(ma)家口(kou)阻截。及至,契丹(dan)步騎萬(wan)余已于河東(dong)(dong)筑壘(lei),正(zheng)掩(yan)護后續渡河。李(li)守(shou)貞(zhen)乘半(ban)渡而(er)擊,拔東(dong)(dong)岸契丹(dan)軍營壘(lei),其軍潰散,溺死甚眾(zhong),西岸之(zhi)兵退走。時戚城(cheng)(cheng)交戰相持不下,耶律德(de)光偽(wei)棄元(yuan)城(cheng)(cheng),伏兵頓(dun)丘(今(jin)(jin)河南浚縣北(bei)),企(qi)圖以示弱誘敵(di)之(zhi)策誘殺晉(jin)軍。適值霖(lin)雨,晉(jin)軍旬(xun)日未出,伏擊落空。
三月(yue)初一(yi),契(qi)(qi)丹(dan)軍(jun)(jun)(jun)(jun)再攻(gong)(gong)戚城(cheng)(cheng),兩軍(jun)(jun)(jun)(jun)鏖戰(zhan)至(zhi)傍(bang)晚(wan),皆死傷(shang)甚眾(zhong)。耶(ye)律德(de)光(guang)乘(cheng)夜(ye)退(tui)營30余(yu)里,隨后(hou)便撤(che)兵(bing)北(bei)歸(gui)。契(qi)(qi)丹(dan)撤(che)軍(jun)(jun)(jun)(jun)后(hou),晉廷遣(qian)軍(jun)(jun)(jun)(jun)收復失地(di)(di),調整部署,擴展軍(jun)(jun)(jun)(jun)備。四月(yue),命(ming)高(gao)行周戍澶州(zhou);遣(qian)李守貞攻(gong)(gong)討(tao)青州(zhou)(今(jin)(jin)(jin)(jin)(jin)屬山(shan)東)的楊光(guang)遠(yuan)叛(pan)軍(jun)(jun)(jun)(jun)。八月(yue),以(yi)劉知遠(yuan)為(wei)(wei)北(bei)面(mian)(mian)行營都統,杜(du)重(zhong)威(wei)為(wei)(wei)都招(zhao)討(tao)使,統領河(he)(he)北(bei)、山(shan)東、河(he)(he)南諸(zhu)地(di)(di)防務;閏十二(er)月(yue),李守貞破青州(zhou),殺(sha)楊光(guang)遠(yuan)。時契(qi)(qi)丹(dan)軍(jun)(jun)(jun)(jun)二(er)次(ci)南下(xia)至(zhi)元(yuan)氏(今(jin)(jin)(jin)(jin)(jin)河(he)(he)北(bei)元(yuan)氏西(xi)北(bei))、分兵(bing)攻(gong)(gong)掠邢(治龍(long)岡,今(jin)(jin)(jin)(jin)(jin)河(he)(he)北(bei)邢臺)、磁(治滏陽(yang),今(jin)(jin)(jin)(jin)(jin)河(he)(he)北(bei)磁縣)3州(zhou)。開運(yun)二(er)年(945年)正月(yue),后(hou)晉護國節(jie)度(du)使安(an)審(shen)琦(qi)等率數萬(wan)兵(bing)于(yu)安(an)陽(yang)水(今(jin)(jin)(jin)(jin)(jin)河(he)(he)南安(an)陽(yang)北(bei)安(an)陽(yang)河(he)(he))南岸列(lie)陣阻截(jie)。十五日,義(yi)成節(jie)度(du)使皇甫(fu)遇率數千(qian)騎前(qian)出偵(zhen)察(cha),至(zhi)鄴縣(今(jin)(jin)(jin)(jin)(jin)河(he)(he)北(bei)臨漳西(xi)南)猝遇數萬(wan)契(qi)(qi)丹(dan)軍(jun)(jun)(jun)(jun),交戰(zhan)百余(yu)合,晉軍(jun)(jun)(jun)(jun)寡不敵(di)眾(zhong),且(qie)戰(zhan)且(qie)退(tui),至(zhi)榆林店(今(jin)(jin)(jin)(jin)(jin)河(he)(he)南安(an)陽(yang)北(bei)),苦戰(zhan)半(ban)日,雙方殺(sha)傷(shang)甚眾(zhong)。黃(huang)昏時,晉將安(an)審(shen)琦(qi)率軍(jun)(jun)(jun)(jun)逾安(an)陽(yang)水往救(jiu),契(qi)(qi)丹(dan)軍(jun)(jun)(jun)(jun)疲敝,撤(che)師北(bei)走。晉軍(jun)(jun)(jun)(jun)乘(cheng)機轉守為(wei)(wei)攻(gong)(gong),集結諸(zhu)軍(jun)(jun)(jun)(jun)于(yu)定(ding)州(zhou)(今(jin)(jin)(jin)(jin)(jin)屬河(he)(he)北(bei)),命(ming)杜(du)重(zhong)威(wei)為(wei)(wei)北(bei)面(mian)(mian)行營招(zhao)討(tao)使統軍(jun)(jun)(jun)(jun)北(bei)上。三月(yue),下(xia)泰州(zhou)(今(jin)(jin)(jin)(jin)(jin)河(he)(he)北(bei)青苑)、克滿城(cheng)(cheng)(今(jin)(jin)(jin)(jin)(jin)河(he)(he)北(bei)滿城(cheng)(cheng)北(bei)),攻(gong)(gong)遂(sui)城(cheng)(cheng)(今(jin)(jin)(jin)(jin)(jin)河(he)(he)北(bei)徐水西(xi)北(bei))。聞(wen)契(qi)(qi)丹(dan)8萬(wan)騎于(yu)虎北(bei)口(今(jin)(jin)(jin)(jin)(jin)北(bei)京(jing)密云東北(bei)古北(bei)口)反(fan)撲將至(zhi),杜(du)重(zhong)威(wei)懼,引兵(bing)撤(che)至(zhi)陽(yang)城(cheng)(cheng)(今(jin)(jin)(jin)(jin)(jin)河(he)(he)北(bei)清(qing)苑西(xi)南)白(bai)團衛村(cun),速扎鹿角為(wei)(wei)寨(zhai)。契(qi)(qi)丹(dan)鐵鷂(yao)(yao)軍(jun)(jun)(jun)(jun)追至(zhi),圍寨(zhai)數重(zhong)。適北(bei)風大起,耶(ye)律德(de)光(guang)遣(qian)奇兵(bing)斷糧道(dao),令鐵鷂(yao)(yao)軍(jun)(jun)(jun)(jun)下(xia)馬(ma)拔鹿角,變騎為(wei)(wei)步,四面(mian)(mian)合擊,縱火揚塵以(yi)助(zhu)其(qi)勢(shi)。
晉將藥元福、皇甫遇等出其不意,率精騎逆風迎戰,殊死拚殺;符彥卿等引萬余騎繼后橫擊;李守貞令步卒盡拔鹿(lu)角(jiao)出擊(ji),契(qi)(qi)丹(dan)軍(jun)(jun)潰(kui)散,棄(qi)馬奪(duo)路而(er)逃。后晉(jin)(jin)(jin)(jin)恃陽城之(zhi)捷,輕視契(qi)(qi)丹(dan),欲伺機(ji)北伐。契(qi)(qi)丹(dan)攻(gong)晉(jin)(jin)(jin)(jin)接連受挫,不甘罷(ba)休。三年七月,耶律德(de)光指使趙(zhao)延壽及瀛(ying)州(zhou)(zhou)刺史劉延祚詐降,誘后晉(jin)(jin)(jin)(jin)出兵(bing)接應。晉(jin)(jin)(jin)(jin)出帝不辨真(zhen)偽,即命杜重(zhong)威(wei)、李守貞等會兵(bing)廣(guang)晉(jin)(jin)(jin)(jin)(今河(he)北大名東(dong)北),悉調京師宿(su)衛禁軍(jun)(jun)歸杜重(zhong)威(wei)麾下,企(qi)圖取(qu)瀛(ying)(今河(he)北河(he)間(jian))、莫(mo)(今河(he)北任丘北州(zhou)(zhou)鎮(zhen)),安定(ding)關南(nan),進取(qu)幽州(zhou)(zhou),蕩平塞(sai)北。十一月,杜重(zhong)威(wei)率(lv)兵(bing)30萬抵瀛(ying)州(zhou)(zhou),契(qi)(qi)丹(dan)將(jiang)高模(mo)翰(han)早已(yi)引兵(bing)潛出。晉(jin)(jin)(jin)(jin)偏將(jiang)梁漢璋率(lv)2000騎(qi)追擊(ji),戰敗身亡。杜重(zhong)威(wei)不救,反倒退兵(bing)武(wu)強(今河(he)北武(wu)強西(xi)南(nan))。契(qi)(qi)丹(dan)軍(jun)(jun)長驅南(nan)下,沿(yan)易、定(ding)向恒(heng)州(zhou)(zhou)(治真(zhen)定(ding),今河(he)北今正定(ding))推(tui)進。杜重(zhong)威(wei)還欲南(nan)撤,遇張(zhang)(zhang)彥(yan)澤返恒(heng)州(zhou)(zhou),乃轉兵(bing)西(xi)行(xing),至中渡橋(今河(he)北正定(ding)東(dong)南(nan)滹沱河(he)上),契(qi)(qi)丹(dan)軍(jun)(jun)已(yi)先于占領。張(zhang)(zhang)彥(yan)澤率(lv)騎(qi)爭奪(duo),契(qi)(qi)丹(dan)軍(jun)(jun)焚橋,兩軍(jun)(jun)遂夾(jia)滹沱河(he)而(er)峙(zhi)。耶律德(de)光遣(qian)別將(jiang)蕭翰(han)迂回晉(jin)(jin)(jin)(jin)軍(jun)(jun)側后,搶占欒城(今河(he)北欒城西(xi)),扼晉(jin)(jin)(jin)(jin)軍(jun)(jun)糧道(dao)、退路。
十(shi)二(er)月,晉將王(wang)清要(yao)求率(lv)兵2000前出(chu)開(kai)道,但杜(du)重威心懷(huai)異志,不許大(da)軍(jun)增援,致使王(wang)清所部皆(jie)戰死,主力亦陷入(ru)重圍(wei)。杜(du)重威以途(tu)窮路末,暗中(zhong)勾通契(qi)丹,謀舉軍(jun)降。耶律(lv)德光佯許立其為帝(di),杜(du)重威伏兵于內,迫將士(shi)出(chu)降(參見陽城、滹(hu)沱之戰)。契(qi)丹軍(jun)即乘晉后方空(kong)虛,揮師南下(xia),直入(ru)汴梁(liang)(今河(he)南開(kai)封)。出(chu)帝(di)奉表報降,后晉滅亡。
此戰,契丹以(yi)騎(qi)兵優勢,實施機動作戰。采取有利(li)則進,不利(li)則退,誘(you)敵深(shen)入的方(fang)略,創造野戰殲敵戰機致勝;晉廷虛(xu)驕輕(qing)敵,悉將京師宿(su)衛禁軍(jun)投入北(bei)伐(fa),主帥(shuai)杜重威(wei)叛降后,致后方(fang)空虛(xu),都(dou)城陷落而亡。