What expression was used in English that "however" and others replaced around 1750?

Prompted by the questions about "despite"/"in spite of" on ELL and EL&U I played in N-gram for in spite of, despite even though, although, however.

After 1750 there is a sharp rise in most of them. Did the general language change to start including negative clauses or did some word fall out of favor to increase popularity of all the rest?

I tried comparing the chart with "but" but despite the steady decline, it didn't register any sharp drops between 1730 and 1800. So what expression was in popular use in the role of these conjunctions, that they replaced?

(footnote: The graph for "However" may be wrong; Ngram refuses to acknowledge "However" can be a conjunction; (however_CONJ) yields a flat zero; so does (however - however_ADJ))

Adding the word "yet" in seems to show a fairly large decline in its usage - could this be the word you're looking for?

It's not exactly a synonym, but notwithstanding seems to have been on the wane since the early 18th Century, just as 'however' was taking off.