When did English stop requiring capitalisation of non-proper nouns? [duplicate]

Capitalisation to this extent wasn't around in Old English, and I didn't remember any in Chaucer's Canterbury Tales, but it seemed exist in some Shakespeare folios and not others, so it certainly hasn't been around since the beginning of written English.

I found this in an actual printed book, The Cambridge Encyclopedia of the English Language (David Crystal), p67, where the internet let me down. It's in the section about emerging orthography in the 16th Century:

Hart recommended his readers to use a capital letter at the beginning of every sentence, proper name, and important common noun. By the 17th century, the practice had extended to titles (Sir, Lady), forms of address (Father, Mistris), and personified nouns (Nature). Emphasized words and phrases would also attract a capital. By the beginning of the 18th century, the influence of Continental books had caused this practice to be extended still further (e.g. to the names of the branches of knowledge), and it was not long before some writers began using a capital for any noun that they felt to be important. Books appeared in which all or most nouns were given an initial capital (as is done systematically in modern German) - perhaps for aesthetic reasons, or perhaps because printers were uncertain about which nouns to capitalize, and so capitalized them all.

The fashion was at its height in the later 17th century, and continued into the 18th. The manuscripts of Butler, Traherne, Swift, and Pope are full of initial capitals. However, the later 18th-century grammarians were not amused by this apparent lack of discipline in the written language. In their view, the proliferation of capitals was unnecessary, and causing the loss of a useful potential distinction. Their rules brought a dramatic reduction in the types of noun permitted to take a capital letter.

It seems odd that Hart's recommendations on capitalisation should have taken root where his suggestions for phonetic spelling have fallen on deaf ears...

"In summary, the practice began with the dawn of written English, probably."

This is incorrect. Although the capitalisation of nouns does occur in German and did occur in other Germanic languages, it didn't occur in Old English or Middle English texts. There was a brief trend, in the 17th and 18th centuries, when nouns were capitalised, but it wasn't standardised and there were no rules about it.

It stopped around the time that English became standardised, which is most likely why it disappeared. With the introduction of "correct" spellings, formatting probably became less necessary.

Still trying to find out why it happened at all. Was it just a fashionable trend? Was there a resurgence of German literature in England?

Capitalization of many--but not all--common nouns is extensive in the America of the 18th century. For example, see the Declaration of Independence.

Americans still capitalized most nouns into the 19th century.

For example, see the following excerpt from one of John Adams' letters to his son. There doesn't seem to be a consistent system.

1804: "braced our feet [not capitalized] against the Bed boards and Bedsteads to prevent us from having our Brains dashed out against the Planks and Timbers of the Ship." Quoted in article in New Yorker magazine May 5, 2014

By the time of the Civil War, the practice seems to have ended (example: the Gettysburg Address does not capitalize common nouns).

I would love to know when, why and how this practice ended.