Subject in sentence with only object pronoun
Let us go
is a correct construction in the English language and definitely not:
Let we go
However, the question is: since us is an object-case pronoun, what is the subject of this sentence?
Solution 1:
It's an imperative, and in English the imperative tense only is possible in the second person.
So grammatically, the subject has to be "you".
It can't be interpreted literally; it's an idiom whose meaning isn't really an imperative that you do something, but a suggestion that we do something.