I'm not a historian but I spend many years in Catholic and Lutheran schools and have studied this topic a lot.

A good book to read about this is Zealot by Reza Aslan. He goes into great detail about Paul and his relationship with the church. A quick summary is that James was Jesus' brother and he and Peter took over Jesus' "movement" when he died, but Paul coopted it so to speak. James and Peter (to a large extent) were very much tied to Judaism and keeping its traditions, while Paul was not - he was able to convert gentiles by not demanding that they have to convert to Judaism to follow Jesus. This attracted a larger following than James and Peter, and Paul although it's not clear if he went to Rome at all gave the stories more of universal or Roman touch at the time when that was the center of the civilized world. As such, his teachings became much more accessible from that center rather than from the backwaters of Judea which many considered that area to be at the time.

Keep in mind that this fued against James and Paul is disputed a lot by Biblical scholars and many believe there was no fued at all. A lot of scholars think Aslan's a hack - but I think he's a brilliant writer and offers great perspective as a non-Christian. The important thing to take away, and why Paul's books have so much appeal in the NT is because of his embracing of those outside of the Jewish faith - even as he himself was a Jew - and not requiring conversion. He also was more like the common man having never met Jesus or having been an apostle many could identify with him as a figurehead as well. Also, he was a bit of a better salesman - he got out there all over Asia Minor and Europe and started building churches and movements - James and Paul were not as eager to see it spread beyond Judea.