Q: Why Is “went” the past tense of “go”? I don’t see the connection. Am I missing something?
A: The connection is another verb that means to move along—the old “wend,” which we don’t often hear today.
English speakers adopted “went,” the past tense of “wend,” because they apparently felt that “go” didn’t have a satisfactory past tense of its own.
In Old English the verb gān (“go”) had a past tense that didn’t come from its own stem. The past tense was completely unrelated: ēode (in Middle English, it was yode).
Even in the West Germanic languages it came from, “go” lacked a past tense based on itself. The reasons for this aren’t known, according to the Oxford English Dictionary.
Some authorities have suggested that the old past tense, ēode, has a prehistoric ancestor in common with the Latin ēo (go, leave). Others have speculated about a connection between ēode and iddja, the Gothic past tense of a similar verb.
But the OED is doubtful, saying only that the Old English past tense of “go” was formed from a base that is “of uncertain and disputed origin.”
No matter how it developed, English speakers apparently weren’t comfortable with ēode (later yode) as the past tense of “go,” because over the course of the 1400s they replaced it with “went.”
This was originally the past tense of wendan (to go, proceed, make one’s way), another Old English verb inherited from Germanic. By the 15th century the verb had long since been shortened to “wend.”
Through much of the 15th and 16th centuries, “go” and “wend” shared the same past tense, “went.” Eventually “wend” developed one of its own, “wended,” at the end of the 1500s.
Today “wend” is no longer used in the sense of “go.” As the OED notes, “wend” and “wended” in modern usage “often imply an indirect or meandering course.”
In this sense, “wend” today resembles another early meaning of the verb, one that’s now lost—to turn or twist. In fact, “wend” is a distant cousin of the verbs “wind” and “wander.”
“The semantic development from ‘to turn’ to ‘to go,’ ” the OED says, “was probably via a sense ‘to turn in a particular direction in order to go.’ It is clear that already in Old English the original idea of turning could sometimes be negligible or lost entirely (a prerequisite for the later use of the past tense went as a suppletive past tense of go).”
(The word “suppletive” refers to an unrelated word that’s used to replace a missing form.)
It’s interesting to note that the verbs “go” and “do” developed along similar lines: “go,” “goes,” and “gone” are parallel to “do,” “does” and “done.”
But “do” had a reasonable past tense from the start, “did” (dyde in Old English), which at least starts with the same letter as “do.”
from Grammarphobia http://www.grammarphobia.com/blog/2016/06/went.html