The Fortifications rule requires that a separate batch of tokens be made, which represent Fortifications. These tokens are of a neutral colour (probably Grey) and may be used by any player.
Forts are built in the Build Ships phase; they cost the same as a Ship token to produce. Likewise, if a player controls a Fortification during this phase, it must be supported in the same manner as a ship, otherwise it is removed. No more than a single Fortification may be built in a single space.
A Fortification is considered to be owned by whoever has the most tokens in the space with a Fortification during the Construct Ships phase. If there is a tie, then whomever owned the Fort last turn is considered to still own it, unless that player has less tokens than the other players with tokens in that space. During the Construct Ships phase, only the owning player may pay tokens to support the Fort; if he does not do so, the fort is removed. In the case of a tie (as above) no new Fort may be built on the space.
A Fort may share a space with any number or type of tokens, including City tokens, Town tokens, Army tokens, and so on.
A Fortification has no effect on any part of the game other than the Conflict phase. During this phase, if both or neither player involved in the conflict posesses the technology Engineering, the player controlling the Fort is considered to gain an extra point of advantage (see Armies, above). If the owning player posesses Engineering, and the other player does not, then the Fort grants two additional points of advantage. If the controlling player does not possess Engineering and the other player does, the Fort contributes no bonus.
After conflict, if a player other than the player who built the Fort is in control of a space with a Fort in it, that Fort comes under his control; he has captured it. It is now up to him whether he wishes to support it or not on the following turn.
If a Fort exists on a floodplain during a flood, is in a space affected by a Volcano or Earthquake, or is in a space where a city is destroyed (not reduced), or if a Fort is on a space with no other tokens (not including ships), then the Fort is removed from the board.