Fortifications

[Chris21wen]

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.

[RangerJoe]

You seem to be referring to fortifications at bases as well as field forts. Units in the field do construct field forts, smaller units make them faster than larger units.

[Chris21wen]

You seem to be referring to fortifications at bases as well as field forts. Units in the field do construct field forts, smaller units make them faster than larger units.

I didn't test unit sizes in the field, never even thought it was a factor. You are correct, larger units do build faster but only if they have engineers.

Only tested a single BF located in Hilo then in hex 183,110, NW Hilo. It only ever constructed if it had engineers. I did monitored others, looking specifically at my on going game (under 26b) the odd units scattered around China during the test under 28.4 but did not find one with forts that have no engineers.

The reference to in the field is referring to the manual section 8.4.4. is wrong, which implies any unit can construct in the field, engineers helping

'Ground units that are in a base/beach hex assume the fortification level of the base/beach, except for units that have a
separate fortification level set at the start of a scenario. Ground units that are not in a base/beach and are not moving will
automatically attempt to build fortifications to protect themselves from attacking enemy ground units. Engineers in the hex
will help in the building of these fortifications. Engineers will only provide this help if the Engineer is in Combat OpMode and
does not have a Destination. Although units without the help of engineers can build fortifications, the work will proceed very
slowly.'

The unit in the pic below has been stationary for 15 days in combat mode. No forts built. The unit to the Se is a BF with no inf or engineer and has also not built anything. Once I gave the inf div it full compliment of eng, 27x combat eng, 3x eng veh and 3x eng it built forts in two days. The BF with the same number of eng built in 6 days.

Screenshot 2026-10-12 082143.png

[BBfanboy]

Unless it has been changed in the latest versions, the game does allow any unit to build field forts. I often keep my HQ unit by itself one hex away from the LCUs it supports. It takes some time (several months, terrain dependent) but the HQs have build as large as 4 field forts. A short test would not show that.

[Diliwitm]

I confirm that artillery units do dig

[Chris21wen]

Unless it has been changed in the latest versions, the game does allow any unit to build field forts. I often keep my HQ unit by itself one hex away from the LCUs it supports. It takes some time (several months, terrain dependent) but the HQs have build as large as 4 field forts. A short test would not show that.

We have a mystery because they are not for me. He's one's, one been in place for 51 days as is, I've another NCPC Bde been in it's location same length of time. Neither have built any forts.

Screenshot 2026-10-13 070134.png (104.41 KiB) Viewed 14 times

Longest amount of time I ran a test for was 20 days, thought 20 days was enough time for any unit to dig a hole. Several months is an long time not to dig in.

These units are on they own as were most of the test I carried out but I did put another unit with engineers in the hex and they do build forts for them, but it takes longer, possible months?

Is it possible your unit have or had others with engineers?

[Chris21wen]

I've noticed something else. If you list ground units in a location the the fortification line tells you if the units are building. In this pic the neither unit had any engineers originally and the line simply said 'Fortifications (0)'.

After 7 days I enabled replacements resulting in eng sqds arriving for both. The turn after they arrived 'Building' was added and the div built level 1 fort in 2 days.

Screenshot 2026-10-13 091312.png (284.19 KiB) Viewed 5 times

Tried it by only turning on replacements for the division and it also indicated building. Moved it out and 'building' disappeared.