The best way of creating generals on the battlefield is by doing it Sevis' way, ie using a captain-led stack with odds of at least 1:1 against it... Works rather well with any kind of heavy cavalry against a small rebel stack or enemy faction stragglers...
But remember this rule of thumb : you cannot have MoH events if your number of generals/family members equals/exceeds your number of territories.
Most MoH generals will be above average regarding stats... So it is one of the best way to add some to your factions, though it requires a certain "ballsiness" to take on an enemy stack with unfavorable odds...
Another good way of adding valauble generals to your faction is by spotting enemy valuable ones and using your princess (or princesses', Spain is the best for this kind of things) to bring them into your family.
Istvan (Hungarian family member) is one of the most valuable that comes to mind in the first game turns...
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