From the 12th century to the 16th century is the Middle English period. There were two major things during this period, one of them was that English became the official language; another was the published of the English edition of Bible. The English edition of literature work occurred in every region of different dialects constantly from the 13th century. Though Latin and French were still regarded as literary language but the thing which is full of creativity and some important works were written in English. English gradually replaced the place of Latin and French from the later half of the 13th century. At that time, English was regarded as official language in political, social life and the standard literary language. In 1382, the Oxford theological professor John Wycliffe translated the Bible from Latin into English due to Religious Reformer. Then he called on people to use the English edition of Bible to attend religious service. 
The Modern English period is from the 16th century till now. During this time, the big event of English is the Revival of Learning. Writers and scholars of the United Kingdom lent many vocabularies from Greek, Latin, French, Italian, Spanish, they even created new vocabularies in order to express new things, new thoughts and new emotions. During this time, English not only became rough-and-tumble but also became the richest. This is related to the Reformation. The Church of England breaks off the Bishop of Roman because of the Reformation. Then the English edition of Bible displaced the Latin edition and the English also displaced Latin and became the language in church. The Scholars of the United Kingdom emphasized the usage of English. 浅析英式英语与美式英语的语音差异(3):http://www.youerw.com/yingyu/lunwen_23745.html