if I own all the previous titles...should I buy the Matrix bundle?

[junk2drive]

That is explained in the readme that you should have clicked in the finished screen of the update but anyway it says

V1.03 - July 9, 2008

New Features/Enhancements

IMPORTANT!!! -Assault Rule Change
The new assault routine runs through the casualty processing, then does an odds ratio melee resolution, then does a combined morale test of the defending stack. If the attacker has at least one non-disrupted unit, wins the melee resolution, and the defender fails his morale check, then the attackers win. For assault purpose only, disrupted units have their morale halved.
Basically, anything the defender can do to increase his morale makes it harder for him to fail the morale test and thus successfully repel the attack The best thing to do when assaulting is ensure you're assaulting with overwhelming force to provide the victory you seek