What determines battle order?

[Vynd]

Has anyone actually demonstrated that faster armies move first? I've seen this claim before, and believed it, but my in game experiences don't seem to support it.

Heck, can anyone say that they have "caught up" with a raiding army before its move? And by this I mean moving into the space it is located in, when it is attempting to move elsewhere, and forcing it to fight instead of move. As opposed to moving to the same place that it moves to, or running into it as the two armies try to move into each other's provinces, or any of the various other tricks people have suggested. A lot of people say that they think it is possible but I can't recall anyone saying they've actually done it.