Does Galatians 2 refer to the Jerusalem Council of Acts 15 or Paul's visit to Jerusalem in Acts 11?

One thing about the Bible that reminds us of God's glory and his perfect plan, is also something that can frustrate those of us who love details and trivia. The Bible is God's story. It only tells us about God and things that are relevant to him. So when we come to read a passage and we can't figure out what historical event it is referring to, we shouldn't take that as some kind of inaccuracy in the book, but a personal nudge that tells us we should probably be focusing more on the message that is being given to us.

Having said that... despite the overall unimportance of the detail of which visit to Jerusalem is described in 'Galatians 2'... figuring out details like this can be of use to us apologetically. In this case, figuring out which visit Paul writes about in Galatians can help us to put a date on when the letter was written, which in turn can give us confidence in how early the things he says were being taught in the Christian church, and go to disproving notions that the message changed over time. So it is with that in mind that I find this debate to have some value.

On to it then... Does Galatians 2 refer to the Jerusalem Council of Acts 15 or Paul's visit to Jerusalem in Acts 11?