Replacements & Reconstitution in the
Operational Art of War

by General Staff

1. Introduction

Losses are a fact of military life, whether they be due to combat (killed, wounded or missing), disease, desertion or, in some cases and for particular and peculiar reasons, the disbanding of entire units. Outlined in this document are the distribution mechanisms by which replacements filter down to understrength units from the inventory pools within the TOAW system. Note that this is a totally separate process from that of reinforcements, which can simply be viewed as an extension of a force's Order of Battle entering the Theatre of Operations on a date later than that at which the scenario starts.

2. Replacement Eligibility

From the manual (italics mine): "Equipment losses are a fact of life on the battlefield. If these losses are not replaced, your units will become less useful over time. Your units are eligible to automatically receive replacements from your force equipment stockpiles if they are under strength, in supply, and not embarked on ships or trains^[i]. In most scenarios, your force replacement stockpiles will be replenished on a regular basis."

3. Replacement Priority

From the manual (italics mine): "In some scenarios, units may have different priorities for receiving replacements. This will usually be mentioned in the scenario briefing". Any unit may have one of the following priorities, as set in the Scenario Editor by the Designer:

How these values reflect how many replacements a unit receives is described in the next section (Replacement Distribution).

4. Replacement Distribution

The results of testing are included in the next two sections, accompanied after that by supporting logs using TOAW's 'toawlog' and 'uberdude' logging switches (add the following after the command line for OPART: toawlog uberdude).

I’ve included both a test (OPART) scenario ( ReplacementDistribution+ReconstitutionTest.SCE) and an Excel S/S ( Replacements.XLS) and would urge readers to perform the tests for themselves, entering the appropriate values in the S/S to compare expected versus actual numbers. Note that there is ALWAYS an element of variability in the results, reflecting some randomness within the replacement distribution routines themselves. Readers might want to vary values to see whether expected #s are still valid- in my experience they are.
The test scenario concerns results for Side=Germany only (Side=UK is added simply so scenario will run), using Rifle Squads only^[ii] across 6 units with varying Replacement Priorities and Assigned/Authorized #s. Replacement Rate for Rifle Squads is 5000. Note the testing only begins turn 2, as this is the first turn replacements are ever issued in any scenario. The scenario is simply cycled and the results of replacement distribution noted in the S/S turn by turn. The numbers should be fairly self-explanatory, but indicate (and the logs would tend to corroborate) that replacement distribution is performed using the following sequence (with U#^[iii] 1 on Turn 2 used as an example here):

1. Each unit's need is calculated for each item of equipment in its ToE. This is the difference between assigned and authorized equipment. So assigned and authorized numbers of 4567 and 9999 Rifle Squads respectively result in a unit need for 5432 Rifle Squads in our U#1 Turn 2 example.

2. A pro-rata figure for available replacements as a percentage of total need on any item of equipment is then calculated. For instance if as on Turn 2 the On Hand and Rate #s for Rifle Squads in the replacement pool total 5000 and the total need is 31272 the pro-rata figure used for Rifle Squads is 5000/31272=15.98% which is rounded down to 15%. Note that units with Replacement Priority=None (i.e. they NEVER receive replacements) have their needs added to the denominator here (thus having a diluting effect on individual unit requests) even though they will never actually receive any replacements^[iv].

3. Each unit's replacement request as calculated in (1) is multiplied by the percentage from (2) to come up with an adjusted individual unit replacement request taking into account overall item availability. In the U#1 example on Turn 2, this is 5432x0.15=814 Rifle Squads^[v].

4. Each unit's pro-rated need as calculated in (3) according to item availability is now pro-rated by its replacement priority- this is in effect what the unit sends in as a replacement request and is the number units should expect to receive, though there appears to be a variability of +/-10-15% and non-integer requests appear to be ignored/discarded. In our example, this would result in a replacement request after all considerations of 814x0.2=162 Rifle Squads- what the unit should expect to approximately receive (in our example it actually receives 163 Rifle Squads).

Note that in (3) it is possible for the need to be so high across all units, and the requests from individual units so insignificant as a percentage of the whole need, that when either step (3) or (4) is calculated, the number returned is a fraction. An example would be a total need of 10000 with a rate of 100 per turn and a unit requesting individually 50 units (at 100% priority- so steps (3) and (4) (at 100% priority) produce a request for 50*100/10000 units=0.5 units). In this case, rounding down, the unit will receive nothing. If all units are in a similar situation on this item of equipment all replacements for the item remain in the pool and can conceivably be ALL taken by reconstituting units passing the tests for reconstitution described under section 6.

An extreme example of a scenario exhibiting this behaviour would be Barbarossa 41, where the Soviet Replacement Rate for Rifle Squads is only 100 per turn, whilst the need, even at start, is around 17000 spread across a good number of units each of whose needs is no more than a few 100. In fact it will take a replacement request (authorized less assigned) by a unit for around 285 Rifle Squads^[vi] before it generates (and receives) a pro-rata request for a single Rifle Squad. Barring no casualties (try it by just cycling through the scenario with no combat), Rifle Squads may remain in inventory until turn 4 or so, when a unit finally manages to break the 'integer barrier'. And this is because the replacements have risen increasing the numerator- from 100/17000 to 400/17000 at which point you need a request for approximately 285/4 or around only 70 Rifle Squads to actually get a single one.

So in this situation it is much more likely that units will reconstitute before any ever receive replacements on high overall need items like Rifle Squads here, though this assumes of course some units are destroyed and are eligible for reconstitution. As units take casualties and the overall need for Rifle Squads mounts ever higher, the request required by a unit to gain a single Rifle Squad replacement will rise from 285 to an even higher number, assuming that replacements cannot be used and go to reconstituting units, resulting in only the rate for the turn (100) entering the pool each turn. Such is exactly the situation in Barbarossa 41's early turns- large numbers of Soviet units are heavily damaged and destroyed, the rate is insufficient to generate more than fractional individual requests which are therefore not met, resulting in replacements being snapped up by reconstituting units as fast as they become available and the unit(s) pass(es) the tests for reconstitution. The process can under certain circumstances feed on itself as the following turn the initial request by an individual unit needed to generate a final supply depot request for a single squad after all modifiers will be even higher as the need (denominator) increases- though the (numerator) rate (all that gets to the pool since on hand has been used for reconstitution in the prior turn) remains the same.

In similar fashion breaking units down can also make it more difficult for them to receive replacements, though it will make it easier for them to pass the reconstitution tests. Say you've got a unit that needs 300 Rifle Squads to get to authorized complement (Step 1). Assume there are only 100 Rifle Squads as rate per turn and across all units there's a need for 10,000- so each request for a single squad is translated into a pro-rata request for 100/10000=0.01 squad (Step 2). The unit therefore generates a pro-rata request for 300x0.01= 3 Rifle Squads (Step 3). Replacement priority for all is normal (60%) so a request for 3 Rifle Squads should translate into actually getting 1.8 (Step 4)- that may be either 1 or 2 depending on the random element introduced by the distribution routines. But if the same unit wanting the same #s was broken down into 3 pieces, each piece would be looking for 1 Rifle Squad through Step 3. Which translates to expecting 0.6 of what's available in Step 4. It may get 1 squad but more likely none with the replacements remaining in the pool.

In circumstances like these reconstituting units are the clear winners in getting replacements- especially since they will take all available on their 'single shot dip' into the replacement pool as described in Section 6.

4.1 Replacement Distribution- Turns 2-5

4.2 Replacement Distribution- Turns 6-9

5 TOAW Supporting Log

5.1 Turn 2

UK replacement requests.
Germany replacement requests.
Rifle Squad : 31272 UK replacement percentages.
Germany replacement percentages.
Rifle Squad : 15% UK requested replacements available.
UK requested replacements remaining.
Germany requested replacements available.
Rifle Squad : 5000

Germany Germany, Germany1 receives 163 replacements by priority 20%.
Germany Germany, Germany2 receives 157 replacements by priority 40%.
Germany Germany, Germany3 receives 329 replacements by priority 60%.
Germany Germany, Germany4 receives 520 replacements by priority 80%.
Germany Germany, Germany4 loses veteran status.
Germany Germany, Germany5 receives 744 replacements by priority 100%.
Germany Germany, Germany5 loses veteran status.
Germany requested replacements remaining.
Rifle Squad : 3087

5.2 Turn 3

UK replacement requests.
Germany replacement requests.
Rifle Squad : 29359 UK replacement percentages.
Germany replacement percentages.
Rifle Squad : 27% UK requested replacements available.
UK requested replacements remaining.
Germany requested replacements available.
Rifle Squad : 8087

Germany Germany, Germany1 receives 285 replacements by priority 20%.
Germany Germany, Germany2 receives 255 replacements by priority 40%.
Germany Germany, Germany3 receives 552 replacements by priority 60%.
Germany Germany, Germany4 receives 878 replacements by priority 80%.
Germany Germany, Germany5 receives 1181 replacements by priority 100%.
Germany requested replacements remaining.
Rifle Squad : 4936

5.3 Turn 4

UK replacement requests.
Germany replacement requests.
Rifle Squad : 26208 UK replacement percentages.
Germany replacement percentages.
Rifle Squad : 37% UK requested replacements available.
UK requested replacements remaining.
Germany requested replacements available.
Rifle Squad : 9936

Germany Germany, Germany1 receives 342 replacements by priority 20%.
Germany Germany, Germany2 receives 307 replacements by priority 40%.
Germany Germany, Germany3 receives 670 replacements by priority 60%.
Germany Germany, Germany4 receives 921 replacements by priority 80%.
Germany Germany, Germany4 loses veteran status.
Germany Germany, Germany5 receives 1187 replacements by priority 100%.
Germany requested replacements remaining.
Rifle Squad : 6509

5.4 Turn 5

UK replacement requests.
Germany replacement requests.
Rifle Squad : 22781 UK replacement percentages.
Germany replacement percentages.
Rifle Squad : 50% UK requested replacements available.
UK requested replacements remaining.
Germany requested replacements available.
Rifle Squad : 11509

Germany Germany, Germany1 receives 477 replacements by priority 20%.
Germany Germany, Germany2 receives 406 replacements by priority 40%.
Germany Germany, Germany3 receives 638 replacements by priority 60%.
Germany Germany, Germany4 receives 849 replacements by priority 80%.
Germany Germany, Germany5 receives 937 replacements by priority 100%.
Germany requested replacements remaining.
Rifle Squad : 8202

5.5 Turn 6

UK replacement requests.
Germany replacement requests.
Rifle Squad : 19474 UK replacement percentages.
Germany replacement percentages.
Rifle Squad : 67% UK requested replacements available.
UK requested replacements remaining.
Germany requested replacements available.
Rifle Squad : 13202

Germany Germany, Germany1 receives 560 replacements by priority 20%.
Germany Germany, Germany2 receives 403 replacements by priority 40%.
Germany Germany, Germany3 receives 623 replacements by priority 60%.
Germany Germany, Germany4 receives 700 replacements by priority 80%.
Germany Germany, Germany5 receives 623 replacements by priority 100%.
Germany requested replacements remaining.
Rifle Squad : 10293

5.6 Turn 7

UK replacement requests.
Germany replacement requests.
Rifle Squad : 16565 UK replacement percentages.
Germany replacement percentages.
Rifle Squad : 92% UK requested replacements available.
UK requested replacements remaining.
Germany requested replacements available.
Rifle Squad : 15293

Germany Germany, Germany1 receives 619 replacements by priority 20%.
Germany Germany, Germany2 receives 396 replacements by priority 40%.
Germany Germany, Germany3 receives 510 replacements by priority 60%.
Germany Germany, Germany4 receives 423 replacements by priority 80%.
Germany Germany, Germany5 receives 287 replacements by priority 100%.
Germany requested replacements remaining.
Rifle Squad : 13058

5.7 Turn 8

UK replacement requests.
Germany replacement requests.
Rifle Squad : 14330 UK replacement percentages.
Germany replacement percentages.
Rifle Squad : 100% UK requested replacements available.
UK requested replacements remaining.
Germany requested replacements available.
Rifle Squad : 18058

Germany Germany, Germany1 receives 586 replacements by priority 20%.
Germany Germany, Germany2 receives 275 replacements by priority 40%.
Germany Germany, Germany3 receives 264 replacements by priority 60%.
Germany Germany, Germany4 receives 112 replacements by priority 80%.
Germany Germany, Germany5 receives 29 replacements by priority 100%.
Germany requested replacements remaining.
Rifle Squad : 16792 Germany Germany, Germany6 evaporates.

5.8 Turn 9

UK replacement requests.
Germany replacement requests.
Rifle Squad : 3066 UK replacement percentages.
Germany replacement percentages.
Rifle Squad : 100% UK requested replacements available.
UK requested replacements remaining.
Germany requested replacements available.
Rifle Squad : 21793

Germany Germany, Germany1 receives 472 replacements by priority 20%.
Germany Germany, Germany2 receives 172 replacements by priority 40%.
Germany Germany, Germany3 receives 110 replacements by priority 60%.
Germany Germany, Germany4 receives 25 replacements by priority 80%.
Germany requested replacements remaining.
Rifle Squad : 21014

5.9 Turn 10

UK requested replacements available.
UK requested replacements remaining.
Germany requested replacements available.
Rifle Squad : 16015

Germany Germany, Germany1 receives 376 replacements by priority 20%.
Germany Germany, Germany2 receives 108 replacements by priority 40%.
Germany Germany, Germany3 receives 38 replacements by priority 60%.
Germany Germany, Germany4 receives 3 replacements by priority 80%.
Germany requested replacements remaining.
Rifle Squad : 15490

6. Reconstitution

From the manual (italics mine): "If your force is at full strength, replacements will appear in the form of reconstituted previously destroyed units built up from replacement equipment. Reconstituted units are always "untried". When units are reconstituted there is a 1 to 4 week delay in their appearance. Reconstituted air units appear at airfields. Other reconstituted units will appear at a scenario specific point (which should be mentioned in the scenario briefing) or near friendly supply sources in urban or road locations. If no friendly supply sources are located in urban or road locations, or if the scenario specific reentry point is not friendly controlled, land units will not be reconstituted. Special forces, Coastal artillery, and fixed artillery units are never reconstituted. Reconstituted airborne and glider units will keep their special icons, but are no longer eligible for airborne movement. Reconstituted units are listed as such in the Expected Reinforcements briefing. The code that decides where to bring reconstituted units back onto the map is quite intelligent. It will attempt to avoid bottlenecks in unit placements while placing units in "good" locations. Unless the scenario designer has placed a reconstitution point there, the chance of a unit appearing at a location isolated by water from the parent formation's first objective is now very low. Land units will reconstitute in "distant" locations only if the distant location is specified as the scenario reconstitution point.".

Note that the Scenario Designer can specify within the Scenario Editor that any unit within a scenario never reconstitutes. Should there be any destroyed units that can possibly reconstitute, and after replacement allocation (if any) to on-board units is complete, a check is made to see whether destroyed units, starting with the unit first in that side's OOB sequence^[vii], can pass the reconstitution criteria, which are:

• Any unit attempting to reconstitute needs 66% OR at least 999 units of its full (authorized) complement of its first line equipment in its ToE listing.

• The 999 units may be less than 66% of the total (authorized) complement.

• These units must be available from the replacement pool AFTER all on-board units have received their allotted replacements from whatever replacements remain.

• Each unit as it attempts to reconstitute will in turn take as much as it can from remaining replacements up to a maximum of a full complement for each and every equipment item in its ToE.

The latter part can be confirmed by looking at the supporting log for Turns 8 and 9. On turn 8 in the log we can see U#6 being disbanded, so that turn 9 starting replacements represent the 16793 from turn 8, including the 1 from the disbanded unit, added to the 5000 rate for the turn for a total of 21793- which is what we see. But on turn 9, replacements are first apportioned out as can be seen, leaving 21014- and indicating replacements are allocated before any reconstitution attempts are made. The figure of 11015 indicating that 9999 has gone to reconstitute U#6 only shows up at the start of turn 10 and already includes the new rate (5000), appearing as 16015 'requested replacements available'.

Note that once a unit has taken replacements from the pool and shows as reconstituting, it takes no more of any equipment item from the pool until it has returned to the map and begins participating in the regular replacement distribution process. Its supply level also remains at the same level- i.e. the level it was when the unit was disbanded or destroyed- until it has returned to the map.

7. Conclusions

1. It would seem from testing that reconstitution occurs AFTER available replacements have been distributed to on-board units using any remaining replacements in the pool.

2. Replacement Distribution occurs in a step-by-step manner- first each unit's need (authorized less assigned equipment) for each piece of equipment in its ToE is calculated and the available replacements (rate and on-hand) for this piece of equipment is divided by the need for it across all units, providing a pro-rata distribution figure (rounded DOWN). This is then applied to each unit's need to produce a unit request pro-rated by availability. Lastly this number is pro-rated by each unit's replacement priority to produce an expected replacement figure per unit. Testing indicates the final distribution per unit may vary by +/-10-15% and that final non-integer replacement requests are often, though not always depending on the +/-10-15% variability, ignored.

3. Testing for Reconstitution occurs AFTER Replacement Distribution for all destroyed/disbanded units in OOB order. Any off-board (destroyed/disbanded) unit attempting to reconstitute needs 66% OR at least 999 units of its full (authorized) complement of its first line equipment in its ToE listing. If a unit finds this minimum number of replacements available it will reconstitute, taking as many units as are available from the replacement pool up to its authorized strength for this item of equipment. For other items of equipment in its ToE, it will take whatever is available or none of the item if none is available.

8. Design Implications

It is possible for reconstitution to be heavily favoured over replacement distribution, when the replacement rate is so low as a percentage of the overall need for a particular item (either as a result of combat or by deliberate scenario design) as to consistently fail to produce pro-rata integer requests at the individual unit level. Units generating such fractional replacement requests usually (within the +/-10-15% variability outlined) receive no replacements.

A warning sign is a low replacement rate (Under 10%) as a percentage of need listed in the TOAWlog.txt file- if TOAW is run so as to generate this file. Designers might want to ensure that in such cases the scenario is performing as they would want as regards Replacement Distribution and, by extension, Reconstitution.

Remedies, should this prove a problem, might include the following:

1. Changing the rate.

2. Changing the overall 'need' by reducing the authorized-assigned differential overall for this equipment item, though it's as well to bear in mind that the overall 'need' is dependent on a variety of factors and will always be dynamic throughout the scenario.

3. Changing the Scenario Time Scale. For example if the time scale for a scenario is weekly and the rate for a particular piece of equipment is 1000 with this generating fractional per unit replacement requests, changing the time frame to bi-weekly might allow for a rate of 2000, which in turn might begin to generate integer per unit replacement requests.

4. Setting the switch for reconstitution for units to 'No' so they cannot 'soak up' replacements as described. In which case replacements are more likely to 'stockpile' if not used to the point where units DO begin to generate integer replacement requests simply because the numerator in the available/need ratio rises (i.e. available is higher).

5. Increasing the replacement priority of units so they are less likely to generate fractional requests.

6. Eliminating or ensuring there are no or few Replacement Priority=None^[viii] units. These can greatly distort Replacement Distribution since they increase the overall item 'need' (denominator in available/need ratio) without actually generating any individual unit Replacement Requests (i.e. they 'dilute' all units Replacement Requests), reducing the pro-rata number of replacements released for distribution to units. So should you want to ensure fewer (or no) units remain in the pool post-distribution for reconstitution you might want to adjust the number of units with Replacement Priority=None downwards. And obviously their correspondent needs, so that the overall item 'need' (denominator in available/need ratio) decreases, increasing pro-rata number of replacements released to units and therefore decreasing units available in the pool for reconstitution purposes.

7. Conversely to 6, should you want to ensure units remain in the pool post-distribution for reconstitution you might want to adjust the number of units with Replacement Priority=None upwards. And obviously their correspondent needs, so that the overall item 'need' (denominator in available/need ratio) increases, decreasing pro-rata number of replacements released to units and therefore increasing units available in the pool for reconstitution purposes.

Note that the remedies mentioned here may have other effects on play (e.g. changing Time Scale)- these should also be carefully considered.

9. Play Implications

Players would be wise to note all the above. Additionally, the consequences of unit breakdowns should also be noted, both as regards the higher probability of each unit generating a fractional replacement request and therefore getting none, and as regards the greater likelihood of destroyed/disbanded broken-down units reconstituting (with a lower 66% of first line equipment threshold)- thereby soaking up replacements that might otherwise eventually reach on-board units through the normal Replacement Distribution process.

Players might also want to take care not to have units destroyed early on in scenarios where there is a large on-hand replacement pool at start that could cause these units to reconstitute- AND where these replacements might be urgently needed to compensate for losses in on map units as soon as possible after scenario start. Otherwise destroyed units may soak up many/all of these replacements leaving none remaining for on map units when desperately needed- the destroyed units of course not reappearing on map for up to 4 weeks. This would be especially true of short time-frame scenarios (1/4 Day Turns) where 4 weeks is represented by 112 turns- in which case you might never get to see reconstituted units return.

10. Footnotes

ⁱNot stated here, though indicated elsewhere (next section in this document), is the proviso that the Replacement Priority must be greater than 0%.
ⁱⁱThough the process is equally valid for other equipment items.
ⁱⁱⁱU#=Unit Number.
^ivIn this example U#6. This can be tremendously important- with the average replacement priority having a far greater effect on overall replacement distribution than any individual unit’s replacement priority, as evidenced in its use in this equation. Take a unit putting in a request for 100 units when 100 are available and its priority is Very High (100%). If it were the only unit with a need it would receive all of them. If another unit with priority=none (i.e. it NEVER gets replacements) also has a need for 100, the first unit will only receive 50% of its request or (50 units) while the second unit will still get none- though it has added its ‘need’ to the equation- resulting in 50 units remaining in the replacement pool.
^vRounding appears to be almost always (brutally) down- judging by the TOAWLog file.
^viSoviet Overall Need for Rifle Squads Turn 2=17142. Rate=100. Priority=Normal (0.6). So 285*(100/17142)*0.6=1.
^viiThanks to Jarek Flis for coming up with most of these.
^viiiAgain, this can be tremendously important- with the average replacement priority having a far greater effect on overall replacement distribution than any individual unit’s replacement priority, as evidenced in its use in this equation. And note also there must be a change in need for there to be any impact both for this remedy and the following (related) one.