Actually d142, I was thinking on it some more and I think any deficit should be as bad as any other deficit, just from a game mechanic’s point of view.
Therefore, if Germany had 1 infantry in London, then England would get a 1 in 6 chance of liberation. If Germany had 7 infantry in London, then England would get a 1 in 6 chance of liberation.
However, to compensate for the reduced odds of liberation, only infantry would be counted as garrison units. Therefore, Germany could have 125 tanks in London and if no garrison infantry were present, then England would have a 1 in 6 chance of liberation.
This is, of course, per round, until the garrison is stationed there.
I was also thinking of territories were 0 IPC or 1 IPC would not need a garrison as there is obviously not much of value in those territories and in some cases, there is hardly a civilian population to rise up anyway. This would free Germany significantly in Africa (2 Infantry for Egypt + 2 Infantry in S. Africa would be all is required, that’s a 12 IPC investment for +9 IPC in gain a round.) And it would free up Japan a bit because they would not have to garrison the Siberian Tundra nor would America have to garrison silly things like New Guinea.