清代張燾《津門雜記》記載： “白河，即北運(yùn)河?！?“兩岸皆白沙，不生青草，故名。又稱潞河?！卑缀雍托l(wèi)河(又稱南運(yùn)河),交流三岔河口，匯于海河，所以白河又指海河。
道光二十年五月(1840年6月),第一次鴉片戰(zhàn)爭(zhēng)爆發(fā)。由于林則徐嚴(yán)密防范，英國(guó)侵略軍進(jìn)攻廣州受挫。英國(guó)政府指示英艦隊(duì)沿海岸線北上，駛向大沽口。名為直接向朝廷投遞書(shū)信要求答復(fù)，實(shí)為執(zhí)行“封鎖大沽?？冢M(jìn)犯天津，威脅北京，以武力脅迫清政府屈服” 的侵華戰(zhàn)略。這樣，京都門戶的大沽?？?，第一次面臨帝國(guó)主義的直接武力威脅。
當(dāng)時(shí)清朝在大沽?？诓](méi)有像樣的戰(zhàn)備設(shè)施，大沽和北塘?？谠械膬勺谂_(tái)均已傾塌，水師營(yíng)又于道光初年裁撤，在英艦隊(duì)北上時(shí)，清政府慌忙命直隸總督琦善加強(qiáng)?？趹?zhàn)備。琦善倉(cāng)促修補(bǔ)了一下舊有的炮臺(tái)，在炮臺(tái)前添置土壘，土壘前筑土埝，埝內(nèi)增筑土炮臺(tái)，并從外地增調(diào)守軍和大炮，用以應(yīng)急。
七月九日，英艦隊(duì)在司令懿律和英駐華商務(wù)監(jiān)督義律率領(lǐng)下，8艘英船(5艘為兵艦)駛抵大沽口外，十日，有一艘進(jìn)入白河口。十四日 (11日),義律向清政府投遞信件，要求派官員到英軍艦上接受照會(huì)。十六日(13日)琦善派千總白含章赴英艦接受照會(huì)。英政府在照會(huì)內(nèi)攻擊林則徐在廣東禁煙，侵犯了英國(guó)權(quán)益，無(wú)理地提出6項(xiàng)要求，限10天內(nèi)答復(fù)。英艦隊(duì)在等待答復(fù)期間，派船深入內(nèi)河測(cè)量水位，窺探炮臺(tái)虛實(shí)，繪制地形圖，以備侵略之用。
八月二日 (8月28日),琦善為欽差大臣，在大沽口與入侵英軍談判。八月四日 (8月30日),琦善在大沽口南岸炮臺(tái)附近帳篷內(nèi)，與義律正式談判。義律堅(jiān)持照會(huì)中的各項(xiàng)無(wú)理要求，琦善節(jié)節(jié)退讓，以 “查辦林則徐”為條件，讓英艦隊(duì)暫撤廣東。當(dāng)時(shí)，連坐在帳篷帷幕外守護(hù)的清朝下級(jí)軍官，看到琦善妥協(xié)媚外的態(tài)度，都暗中表示不滿。會(huì)談進(jìn)行了6個(gè)小時(shí)，結(jié)束后，琦善設(shè)宴招待。席間，侵略者 “嬉笑怒罵” ,竟 “有舞洋槍飛刀座上者” ; 而琦善卻表現(xiàn)出 “隱忍受辱”的窘態(tài)。八月二十日(9月15日),英艦隊(duì)退出大沽口南返。
白河投書(shū)，是外國(guó)侵略者第一次武力威脅天津，英國(guó)侵略者在大沽口40天的交涉活動(dòng)，對(duì)天津以后的社會(huì)變化和整個(gè)鴉片戰(zhàn)爭(zhēng)，產(chǎn)生了嚴(yán)重的不良后果。

·1840年8月，英軍侵犯大沽口

The Tianjin Annals compiled by Zhang Tao of the QingDynasty reported that,"the Baihe River,or the NorthCanal,It is also called Luhe River." The Baihe River andthe Weihe River (or South Canal) joins at Sanchakouinto Haihe River,so the Baihe River also refers to HaiheRiver.
In June 1840,the First Opium War broke out.The British army were stalled by Lin Zexu`s strongdefense in Guangzhou. The UK Government orderedits fleet to sail northward along the coastline to reachthe Dagu Emplacements at last. The British forcesthen delivered a letter to the government of the QingDynasty. The strategy of British army was to "lockDagu Emplacements,occupy Tianjin,menace Beijingand force the Qing Dynasty to surrender". As the gateto Beijing,the Dagu Emplacement was under directmilitary attack from the imperialism.
The defense of Dagu Emplacement was fragile.Its two emplacements in Dagu and Beitang had alreadyfallen. Then the navy was dismissed. When the Britishfleet went north,the Qing Government hurriedly orderedQi Shan,the Governor-General of Zhili,to strengthenthe defense of the sea. Qi repaired the old emplacementsand built more earth bases. On the bases were cannons.He also dispatched soldiers and cannons from outside ofTianjin in urgency.
On July 9,the British fleet composed of eight ships(five warships) led by Commander Charles Elliot andUK Business Represent ative Charles Elliot arrived atthe Dagu Emplacement. On July 10,a warship enteredthe mouth of Baihe River. On July 11,Charles Elliotsent a letter to the Qing Government,demanding it toappoint an official to receive a note on the British ship.On 13,Qi Shan sent Bai Hanzhang,a general,on boardto receive the note,in which the British Governmentclaimed that Lin Zexu`s burning of opium in Guangzhouhad harmed UK`s interest and proposed six requirementsfor reply within 10 days. When waiting for a reply,theBritish fleet surveyed the depth of the inner water andthe deployment of the emplacements. It also drew mapsfor invasion preparation.
On August 28,Qi Shan acted as the imperialenvoy and negotiated with the invaders at the DaguEmplacement. On August 30,negotiation was held ina tent near the emplacement of the south bank of theDagu Emplacement. Charles Elliot insisted on all theunreasonable requirements raised in the note. Qi Shancontinued to give way and agreed to punish Lin Zexuif the British fleet retreated from Guandong Province.Even his subordinate officials were disappointed andangry at Qi Shan`s compromise. The negotiation lastedfor six hours and after that Qi Shan treated the invadersa banquet. During the banquet,the British were veryimpolite and even played weapons before Qi Shan,whotolerated all the insults. On September 15,the Britainfleet retreated from the Dagu Emplacement and returnedto south.
Delivering a note on Baihe River was the firstmilitary menace by foreign invaders in Tianjin. The40-day activities of British invaders at the DaguEmplacement produced a bad influence on Tianjin`ssociety and on the process of Opium War in 1840-1842.

·1840年8月30日，琦善與義律談判 (潘恩春 油畫(huà))