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Find groups of history buffs, like minded people to talk to him and expand his worldview. fuck even direct him to /his/ if you can't find anything else. People need a group or they go cuckoo bananas and off themselves.
Does your sons school have a history club? A debate group? A cycling team? Don't force him to do these things, but show him they are an option, introduce him to someone from these groups as they'll likely be more able to pique his interest than you with their knowledge of his interests.
Ask him to come fishing/camping/hiking/cycling with you and have dad and son talks, you don't need to be good at it, you just need to be interested in his thoughts, and you already seem to be worried about him so it shows you're not a failure father.
Everyone needs a dad, give him the dad you wished you'd had, but not so far as to alienate yourself from him, Godspeed dadanon.