第二次鸦片战争时期的第三次大沽口之战,始于咸丰九年十月 (1859年11月) ,英法政府为了对第二次进攻大沽口的惨败进行报复,分别再次任命额尔金、葛罗为驻华公使,征调大批舰艇,组成新的英、法联军,由英海军上将贺布、陆军中将格兰特、法陆军中将孟托班,任舰队正、副司令,继续扩大侵略战争。
        咸丰十年六月(1860年7月),英舰173艘,法舰30艘,载兵25000人,驶至大沽口外水域,停泊于大沽与北塘间距岸8里的海面上。这时大沽口防线上清军有10000余人,分别驻守于大沽南、北炮台和草头沽、于家堡、新河、新城、塘沽、营城一带的营盘内,仍由僧格林沁督率。大沽炮台又增加了从沉水敌舰中捞出的洋炮12尊;大沽村外挖濠沟一道,塘沽筑壕墙一道,海口增设万斤铁戗,营城新筑炮台4座。当英、法的庞大舰队驶抵大沽口外时,僧格林沁认为,只要加强炮台正面防御,便可万无一失,并向朝廷保证,“此次决战,必操胜算” 。
        清政府对战局依然心存疑虑,希望通过美、俄调停,让英、法公使从北塘登陆入京换约,并发出在北塘为公使登岸让出一条通道的命令。僧格林沁则认为,北塘营垒过于靠近民居,不易防守,坚持主张全面撤除北塘防务。于是 “北塘的炮位兵丁悉数撤去” ,把撤出的大炮、兵丁布置在大沽、营城一带。
        停泊在大沽口外海域的英、法舰队,鉴于上次失败的教训,这次未敢轻易从正面进攻炮台,而是伺机寻找炮台大炮射程之外的登陆地点。策划从背后包抄炮台。俄国新任公使伊格那切耶夫暗地向英、法联军透露了 “北塘防务空虚” 的情报。英、法舰队决定乘虚从北塘登陆。

        

·1860年8月1日,英、法侵略军占领北塘炮台

        六月十六日 (8月1日)下午,英、法舰船30余艘、军队5000人,乘海潮偷偷从北塘登陆,并顺利地把炮车、马队运上北岸,迅即侵占了已经撤防的北塘炮台。英、法侵略军占据北塘镇,大肆对居民进行杀戮抢掠。
        六月二十六日 (8月12日),联军万余人,分头向塘沽以西的新河、军粮城进攻。僧格林沁从塘沽和新河,抽调2000余马队进行迎击。联军排成散兵以排枪阻击马队冲锋,炮车又集中炮火连续轰击,清军马队几乎全军覆没。六月二十八日(8月14日),联军进攻塘沽,激战2个小时,占领了塘沽壕墙,清军退守到大沽北炮台。七月一日 (8月17日),联军从大小梁子渡过海河到达南岸,包抄南炮台的后路; 同时,海上的敌舰也从正面进逼。大沽各炮台陷于前后夹击的危险境地。此时僧格林沁已丧失抗击信心,对南北炮台“能否扼守,实无把握” 。转天,直隶总督恒福向联军求和,遭到拒绝。七月五日 (8月21日)晨,联军倾巢而出,攻击北岸炮台。炮台守军英勇作战,奋力抵抗,各炮台一齐开炮策应。激战到上午10时,炮台的弹药库被击起火,北炮台失陷。这次战斗毙伤敌人200余人; 清军伤亡1000余人,提督乐善牺牲。北炮台失陷后,僧格林沁弃阵而逃,连夜逃回通州。直隶总督恒福以避免居民受损为借口,拱手向联军让出南岸各炮台,大沽口防线全面崩溃。
        The third Dagu battle took place in November 1859(the ninth year of Emperor Xianfeng). To revengetheir defeat,Britain and France appointed Lord Elginand Gloria as their respective ambassadors to lead thenew allied forces in warships. The UK admiral Hope,Lieutenant General Grant,and the French LieutenantGeneral as commander general and deputy commandersgeneral were send to expand the war of invasion.
        In June 1860,173 British warships and 30 Frenchwarships carrying 25,000 soldiers arrived at the opensea of the Dagu Emplacement,eight miles away fromBeitang. At the Dagu line of defense,10,000 soldiersunder the leadership of Sengge Renchin stationed atDagu north and south emplacements and the barracksof Caotougu,Yujiabao,Xinhe,Xincheng,Tanggu andYingcheng. The Dagu Emplacement was reinforced withthe 12 cannons fished out from the sunken warshipsof the enemies. A trench was dug out for Dagu; a wallwas built for Tanggu; an iron block of 5,000 kilogramswas put at the seaport; and at Yingcheng,four newfortifications were constructed. When the allied forcesarrived,Sengge Renchin promised the Qing Court thatthe front defense of the emplacement would ensure the success.
        But the Qing royal government was still worried.They wished that British and French ambassadors wouldgo to Beijing by Beitang for treaty exchange via Americaand Russia`s intermediation. They also issued a passfor the ambassadors by Beitang. According to SenggeRenchin,battalion of Beitang,near civilian houses,was not suitable for defense,so he ordered to retreatthe cannons and soldiers and placed them at Dagu andYingcheng.
        Because of the previous failure,the British andFrench fleets did not attack the emplacement directly.They wanted to land out of the cannon shot and outflankthe emplacement. The Russia`s new ambassadordisclosed Sengge Renchin`s retreat from Beitang,so theBritain-France army decided to take the advantage of the weakness.
        In the afternoon of August 1,5,000 enemysoldiers by 30 warships landed Beitang while tiding.They carried cannons and horses to the north bank andoccupied the emplacement quickly without meetingresistance. They robbed and killed many civilians there.
        On August 12,about 10,000 enemies attackedXinhe and Junliang cheng,which located south ofTanggu. Sengge Renchin drew 2,000 cavalries fromTanggu and Xinhe for counterpunch,but all of themwere killed by the guns and cannons. On August 14,theenemies broke through the walls at Tanggu in two hoursand the Qing army retreated to the Dagu Emplacement.On August 17,the enemies crossed Meihe River andreached the south bank and their warships attacked inthe front. The Dagu Emplacement was under blanketattack. Sengge Renchin lost his confidence of resistance.On the next day,Heng Fu,Governor-General of Zhili,sued for peace but was denied. At the dawn of August21,the enemies turned out in full force when attackingthe north emplacement but met with courageousresistance from the defending troops with support fromthe other emplacements. At 10 am,the ammunitiondepot was on fire and the north emplacement lost. Twohundred enemies were killed but 1000 Qing soldiers diedincluding Governor Le Shan. After the loss of the northemplacement,Sengge Renchin fled to Tongzhou for lifeat night. With the excuse of protecting civilians,HengFu gave up the south emplacement and the Dagu defenseline broken down by the allied invaders.

        

·1860年8月1日,英、法侵略军占领北塘炮台