This page is based on a section of User blog: Robin Patterson/Col1 FAQ by Toby Douglass. Comments on it should be on its talk page rather than on the blog.Material copied from http://45mercystreet.com/computing/col94/index.html with specific (e-mail) permission of author (Toby Douglass)
The computer AI is pretty dumb. A sound tactic is to move a combat unit into a high defensive bonus square next to an enemy; the next turn, the AI is likely to attack that unit.
With regard to the Expeditionary Force, there are SO many hostile units that attacking them becomes amazingly tedious. I find it's best simply to have a Fortress with 100% Liberty Bells and plenty of cannon; the computer launches attacks far more quickly than you can and rapidly gets through all their attacking units. It's much less hassle than trying to do your own attacks - and it saves you having to build up Dragoon forces. Just build cannon.
Normal colonists are captured when they lose in combat. There are three exceptions to this; scouts, missionaries and pioneers (expert or not) all die when they lose in combat. It's best to leave the pioneers to set up a colony and then attack them.