Did you know that, during an assault, reinforcement troops can be in a province and do not have to be part of the ongoing assault? Troops in motion in a province are not part of the assault.
As posted by Stonewall in a separate thread:
"When you press F12, the console comes up. If you then type in "info spa" you will pop up a list of what the Spanish ai is doing with regards to money. Sometimes they have no plans for spending. Often times their plans will be to send emrchants or colonists. Sometimes, the ai will be saving money for a manfactory. Also, the command gives you the amount of money in the ai country's treasury and what its estimated yearly income is. I've never been able to figure out what the 2 generals with 2 plans stuff means. I think its just the ai's troop movements, but really don't know. More importantly, by doing this little cheat, you can get a glimpse of what the ai is thinking."
"If you right click on the minimap you can get an option to overlay various unit/revolt/conquistador/leader locations on the world map. I use this to keep track of lots of explorers going in different directions."