From an archived post on the crimson-users mailing list:
To attack ground enemies: The artillery has a shotrange of 6, which is long, second to the railguns which have the longest shotrange, 7, while the scout and torpedo boat have a shotrange of 2, and others 1.
To attack enemies in the air: The Anti-aircraft guns and the carrier are most powerful, with a shotrange of 6. For others, including heavy tanks, infantry, hovercraft, personnel carriers, patrol boats, and anti-air tanks, the shotrange is only 1.
Tactic hints: Use your artillery well, it is one of the most valuable units in this game, they should not be sacrificed.
The infantry is the only unit capable of capturing cities, factories, camps, etc.
Watch the grade factor, more experienced units are able to stand longer under enemies' fire, and pack a heavier punch.
If the carrying unit is damaged, so is the carried units, usually.