在鸦片战争中,发生过两次定海军民抗英保卫战.第一次定海之战,正式揭开了鸦片战争的序幕;第二次定海之战,是整个鸦片战争中打得最激烈、守卫时间最长、英军损失最惨重的一战.定海失守,使英军第一次用武力侵占了中国领土,清政府第一次丧师失地;定海陷落,是中国领土主权沦丧的开始,也是中国沦为半殖民地国家的开始.但是,过去一些史书中,对这一重大历史事件,或者缺漏,或者舛误者不少.这是一个缺陷. During the Opium War, two naval and civilian anti-British defensive battles took place. The first battle of the sea set off the prelude to the Opium War. The second battle of deciding the sea was the most intense and guarded war in the Opium War The longest war in the history of the United Kingdom was the most tragic loss of the British army. The fall of the Dinghai Sea caused the British troops to occupy the Chinese territory for the first time by force and the Qing government lost their land for the first time. The fall of the Dinghai Sea was the beginning of the demise of China’s territorial sovereignty. China became the beginning of a semi-colonial country, but in some history books, there were either many missing or no wrongdoings in this major historical event, which is a flaw.