Hi Zee. Just to let you know, although "which" technically is ok in this example, it is normally used for nonrestrictive clauses. "Which ended World War II" is necessary information needed to distinguish the treaty in question from any other treaty. We use the relative pronoun "that" when the clause required is restrictive. So, "that" would be a better choice. Just a friendly suggestion.

Which

Sorry, but your question isn't correct. That agreement was signed on 10.02.1947.