IIRC there were also some percents that between 2 dates Kentucky would secede or decide to remain in the Union and other percentages if at the end of the second date, if Kentucky were still neutral that determined whether it seceded or remained in the union.
About the penalty of entering Kentucky too soon, the basic turn of events is:
- Side-a buys the 'invade Kentucky' chit.
- In the next turn side-a can now invade Kentucky at no penalty. Most Kentucky units will belong to side-b (not all; the non-invading side get's the most units).
- Side-b gets a news paper message that Kentucky has been invaded.
- Side-b can now also enter (quasi invade) Kentucky, but because Kentucky has not yet declared that it has allied itself with side-b, if side-b sends units into Kentucky, they will be 90% decimated as if through attrition. This is to simulate Kentucky also fighting side-b too, although side-a invaded first.
- The second turn after the invasion chip was purchased, side-b gets a news paper message that side-b is moving troops into Kentucky to support it against the invasion from side-b and that Kentucky has sided with side-b. Side-b can enter Kentucky normally without penalty.
IIRC the probability that baring an invasion Kentucky would secede was greater than it remaining in the Union.
There was also an explanation that if you had unlocked units in a region adjacent to Kentucky, these units would increase the probability that Kentucky would side with the other side by a percentage cumulative to the number of units adjacent to Kentucky.
Units in a river location (on generic or real transports) with a region belonging to the unit's side adjacent to the river location do not affect this, as they are considered to be transporting over the owning sides own river location. For example, the US could have units on transports adjacent to Louisville without affecting Kentucky's secession probability, because there is an adjacent US land region.
There was also and explanation to what happens if both players buy the invasion chit in the same turn and the percentages of it seceding or remaining in the Union.
The whole thing was quit extensive.