Many editors use the past-perfect tense ("it had happened", "they had done it") to indicate that something occurred a "long" time ago. This is incorrect. The pluperfect (past perfect) indicates that the event occurred before some other time that is also in the past. It should be used only when two conditions are satisfied: (a) the intermediate time is specified, and (b) the fact that the event occurred before that time is important (notable). In all other cases, the simple past tense should be used ("it happened", "they did it").