That isn't the English subjunctive.

You're correct that this construction expresses the same thing that another language might express by marking a non-indicative mood on the verb, but it would not conventionally be said to use a non-indicative mood. That went is a normal past-tense indicative verb and the modality is expressed by the whole structure of the clause, not just by the inflection of the verb.

In linguistics there's a whole set of parallel vocabulary where one set is for grammatical forms and the mirror set is for the semantics usually expressed by those forms. So you have grammatical "tense" and semantic "time" or grammatical "mood" and semantic "modality". You got the modality right, but not the mood.

Compare the conventional analysis that he will be there tomorrow expresses future time, but is not in future tense because there is no English future tense.