Makes me think of this anecdote that I’ve always liked from The Story of English, by Robert McCrum, William Cran and Robert MacNeill:
“Going by the written record alone, the supremacy of Norman French and Latin seems total. In 1154, the English monks who wrote The Anglo-Saxon Chronicle abandoned their work forever. A great silence seems to descend on English writing. In court, church, and government circles, French was established as the smart and Latin as the professional language. There is, for instance, the story of Bishop William of Ely, Chancellor of England during the reign of Richard the Lionheart (Coeur de Lion). Disgraced politically, the bishop tried to escape from England in 1191 disguised as a woman and carrying under his arm some cloth for sale. He reached Dover safely but was discovered when he was asked by an English woman what he would charge for an ell of cloth. He could not reply because he knew no English – and it was inconceivable that his low-born captors could speak French.”
The authors go on to say:
“At the end of the thirteenth century, Edward I, who was very conscious of his Englishness, whipped up patriotic feeling against the king of France, declaring that it was ‘his detestable purpose, which God forbid, to wipe out the English tongue’.”
And the bubonic plague gets a mention:
"The Hundred Years War with France (1337-1454) provided a major impetus to speak English, not French. At the same time, the outbreak of the mysterious disease known as ‘The Black Death,’ by making labor scarce, improved and accelerated the rise in status of the English working man (a process that culminated in the Peasants’ Revolt of 1381). It caused so many deaths in the monasteries and churches that a new generation of semi-educated, non-French and Latin speakers took over as abbots and prioresses. After the plague, students at school began to construe their French and Latin lessons in English not French, to the obvious detriment of French.
“English now appears at every level of society. In 1356, the mayor and aldermen of London ordered that court proceedings there be heard in English; in 1362, the Chancellor opened Parliament in English. During Wat Tyler’s rebellion in 1381, Richard II spoke to the peasants in English. In the last year of the century the proceedings for the deposition of Richard I (together with the document by which he renounced the throne) were in English. Henry IV’s speeches claiming the throne and later accepting it were also in English. The mother tongue had survived.”