Fortifications
Posted: Wed Oct 07, 2026 6:58 am
Been digging into, excuse the pun, forts under 28.4 and 26b and I've found the manual is incorrect on forts in a number of ways. See sections 8.4.4, 8.10 and 9.5.
8.4.4 implies any ground unit can build a fort in the field, it certain should be the case for level 1-3, but I can find no evidence that units with no engineers can build forts. This is from the test under 28.4 and a current on going game under 26b. In the latter I've got a number of units with no engineers who have been in place for over fifty turns and not one has dug in.
The second problem implies fort construction speeds and costs are based on the SPS. This is not the case. It is based on the current size of the fortifications. With the same number of squads at any level with any SPS it takes exactly the same length of time to construct a level 1 fort, be that in a dot base or say San Francisco. The same goes for any other level.
The rate at which fortifications are built appears to be pretty much linear with each level taking what appears to be 16 times longer than the previous level, although I've not tested anything over 3, (takes to long and I lacked the will power).
At the very basic level a 12 man Eng sqd takes 3 turns to construct a level 1 fort as follows:
Initiating a level 1 fort automatically sets the rate to 10% completed. Each turn the sqd spends building adds a further 30%. So after the first turn the rate will be 40%, second 70% and third 100%, 3 days. Supply costs for the first turn is 12, on each successive turn it cost 3 supply. Overall the supply cost for one sqd building a level 1 fort is 18. This difference may have something to do with the initial 10%?
Now the tricky bit, increasing the number of sqds does not multiply the build rate by the number of sqds. E.g. 2x Eng does not make it 60%. Instead, each extra sqd adds just 5% to the build rate. The effect is that a 13x Eng sqds can construct a level 1 fort in one day at a cost of 9 supply. Faster using less supply than a single sqd.
Tests have shown that it takes these 13x Eng sqds 16 days to go from level 1-2 and 52x Eng sqds can do it in approx. 4 days. The same 52x Eng sqd takes approx. 16 days to go from 2-3.
I've test other level up to 6 and no matter what level of fort you construct, an equal number of eng sqds uses the same amount of supply per turn. What changes is the construction time hence overall supply increases. Exactly how much depends on the number of engineers working but this is also not straight forward.
Every turn an single engineer squad spends fortifying cost 3 supply. However as the number of engineers increases the cost in supply seems to fall for a build this cost per squad is reduced. For instance a 13x Eng it's 9 supply, 52x Eng costs 28 and 130x Eng it's 67 per day.
To go from level 1-2
1x Eng sqd spends 3 supply per day over 33 days = 99 supply total
13x Eng Sqds spends 9 supply per day over 16 days = 144
52x Eng Sqds spends 28 supply per day over 4 days = 112.
130x Eng Sqds spend 67 supply per day over 2 days = 134.
All of these figures tare subject to some small variations, but not much, and I do not know the exact formula.
The exception to any of this is Level 7-9. At these levels in costs more than 3x the normal supply cost per turn, slightly over 200 per turn for a 130x Eng, not the normal 67 per day. You also need 25K supply to even start build these levels.
8.4.4 implies any ground unit can build a fort in the field, it certain should be the case for level 1-3, but I can find no evidence that units with no engineers can build forts. This is from the test under 28.4 and a current on going game under 26b. In the latter I've got a number of units with no engineers who have been in place for over fifty turns and not one has dug in.
The second problem implies fort construction speeds and costs are based on the SPS. This is not the case. It is based on the current size of the fortifications. With the same number of squads at any level with any SPS it takes exactly the same length of time to construct a level 1 fort, be that in a dot base or say San Francisco. The same goes for any other level.
The rate at which fortifications are built appears to be pretty much linear with each level taking what appears to be 16 times longer than the previous level, although I've not tested anything over 3, (takes to long and I lacked the will power).
At the very basic level a 12 man Eng sqd takes 3 turns to construct a level 1 fort as follows:
Initiating a level 1 fort automatically sets the rate to 10% completed. Each turn the sqd spends building adds a further 30%. So after the first turn the rate will be 40%, second 70% and third 100%, 3 days. Supply costs for the first turn is 12, on each successive turn it cost 3 supply. Overall the supply cost for one sqd building a level 1 fort is 18. This difference may have something to do with the initial 10%?
Now the tricky bit, increasing the number of sqds does not multiply the build rate by the number of sqds. E.g. 2x Eng does not make it 60%. Instead, each extra sqd adds just 5% to the build rate. The effect is that a 13x Eng sqds can construct a level 1 fort in one day at a cost of 9 supply. Faster using less supply than a single sqd.
Tests have shown that it takes these 13x Eng sqds 16 days to go from level 1-2 and 52x Eng sqds can do it in approx. 4 days. The same 52x Eng sqd takes approx. 16 days to go from 2-3.
I've test other level up to 6 and no matter what level of fort you construct, an equal number of eng sqds uses the same amount of supply per turn. What changes is the construction time hence overall supply increases. Exactly how much depends on the number of engineers working but this is also not straight forward.
Every turn an single engineer squad spends fortifying cost 3 supply. However as the number of engineers increases the cost in supply seems to fall for a build this cost per squad is reduced. For instance a 13x Eng it's 9 supply, 52x Eng costs 28 and 130x Eng it's 67 per day.
To go from level 1-2
1x Eng sqd spends 3 supply per day over 33 days = 99 supply total
13x Eng Sqds spends 9 supply per day over 16 days = 144
52x Eng Sqds spends 28 supply per day over 4 days = 112.
130x Eng Sqds spend 67 supply per day over 2 days = 134.
All of these figures tare subject to some small variations, but not much, and I do not know the exact formula.
The exception to any of this is Level 7-9. At these levels in costs more than 3x the normal supply cost per turn, slightly over 200 per turn for a 130x Eng, not the normal 67 per day. You also need 25K supply to even start build these levels.