Translation:The poor man did not know what happened.
What is the rule on adjectives? For some reason I had a feeling that pobre should follow hombre. Or am I confusing some other part of speech?
Both are ok, although they mean something slightly different. There are some adjectives in Spanish that change meaning depending on whether they come before or after the noun. "El pobre hombre" means "poor" as in "The unfortunate man", whereas "El hombre pobre" means "poor" as in "The man of lower financial status".
Isn't there supposed to be an accent over the o in "supo"? It is the past ("didn't know")
Wouldn't, "The poor man did not know what HAD happened" suffice as well?