Fortress rules and a supply rule change/clarification

I have been reviewing these rules while processing the May II movement orders. I'm sending around a reminder of how fortresses work and, as a result of my rereading, a change/clarification of how supply sources work.

Reminders:

An army must stop on entering an enemy fortress area, unless a friendly force is already present assaulting or besieging the fortress.

To successfully assault a fortress, an enemy army must have more infantry and artillery units than the value of the fortress (in this scenario all fortresses are 3s, so attackers must have at least 4 infantry and/or artillery). If there are enemy infantry/artillery inside the fortress in addition to the garrison, this will increase the value of the fortress. The turn *after* a siege is established, the attacker may attempt to assault the fortress; even if he fails, the chance to successfully assault next turn goes up, as long as there are more attackers than the modified value of the fortress. A failed assault seems not to cause any appreciable loss to the attacker, though I need to check the discussion group logs and errata to be sure (this seems too generous).

To simply *besiege* a fortress (not assault it), an army must have at least 4 infantry units and 1 cavalry unit. At the end of each turn of siege, there is a (noncumulative) chance the fortress will fall.

If a fortress falls, its garrison become prisoners and if it was a supply point for the defenders, it now becomes a supply point for the attackers.

Change/Clarification:

I had not noticed this last part of the siege consequences before, so I had assumed that supply points (unlike depots) always remained either friendly and functional or friendly and nonfunctional if controlled by the enemy, but did not become enemy supply points. Since friendly fortress supply points can become enemy supply points if captured, I can only assume that unfortified supply points change sides when they are captured too.

This would mean that when Pilsen was captured by Frederick, it became a Prussian supply point.

Maybe everyone else had already twigged to this and I'm the slowpoke. :-)