The Severskii Donets River Crossing Operation

This is another piece of TNDM analysis from William (Chip) Sayers. He will be doing a presentation at our Historical Analysis conference: Who’s Who at HAAC – part 1 | Mystics & Statistics (dupuyinstitute.org). Now, I have questioned the Ukrainian estimates of overall casualties: The Ukrainian casualty claims are inflated – part 1 | Mystics & Statistics (dupuyinstitute.org). This post by Chip Sayers makes the point that the estimates of 400+ Russian casualties in this river crossing operation is believable. 

The William (Chip) Sayers piece:

The objective of this set of model runs was to explore the failed Russian river crossing operation of the Siverskiy Donets.  Ukrainian photos of the battlefield aftermath showed vividly the carnage wrought by modern defenses when properly warned and deployed. 

Ukrainian reconnaissance detected the Russian preparations to cross the Siverskiy Donets at least 3 days prior to the river crossing operation, which gave them time to bring up reinforcements and prepare a defense.  According to uawardata.com, The 79^th Ukrainian Air Assault Brigade was defending the sector, while one or two Battalion Tactical Groups from the 35^th and 74^th Mechanized Brigades of the 41^st Combined Arms Army were in the area of the attack.  The Institute for the Study of War reports that it was a BTG from the 74^th Mech Brigade that conducted the attack.

The vulnerability of attacking forces in a river crossing operation is such that surprise and support are necessary to preclude catastrophic losses.  Clearly, the Russian BTG failed to achieve surprise — it is unknown how well supported they were, but the scale of their losses indicates that whatever support they had was probably inadequate.

I set up the battle with the following forces:

Russian: one mechanized BTG from the 74^th Mech Brigade with support from half the guns of the 120^th Artillery Brigade (the 41^st CAA’s sole artillery brigade) and 30 Mi-24 attack helicopter sorties.

Ukrainian: one battalion from the 79^th Air Assault Brigade plus a battalion slice of brigade assets (the brigade apparently was covering a large frontage and probably couldn’t afford to devote more to the battle).  Assuming the Ukrainian Army productively used the warning time they had to bring up supporting fires, I gave the defenders an Urgan MRL battalion from the 27^th Rocket Artillery Brigade.  Just for fun, I also gave them ~10% of the Switchblade “kamikaze” UAS that the United States has sent (100 x Switchblade 300 anti-personnel drones and 20 x Switchblade 600 anti-tank drones). 

The Siverskiy Donets is only about 50m wide at the crossing point, and the ground is heavily forested, though relatively flat.  As best as can be determined from aerial video imagery, the battlefield is actually too small to support an attacking battalion.  Soviet motorized rifle battalions attacked on a minimum frontage of 1 kilometer, while a Russian BTG is somewhat beefier organization.  The Siverskiy Donets makes a partial loop at the point of attack and a kilometer attack zone would have taken the entire frontage of the loop such that Russian troops on one side might have been firing into the faces of their compatriots attacking at the other end of the line.  This suggests that they probably attacked on no more than a single company frontage (400m), with four companies in echelon.  This is not a formula for success in an opposed river crossing.

For the base case, I did not give the Ukrainian side a CEV advantage, nor surprise to either side.

Results:

After a full day of battle on 11 May, the Russians were decisively repulsed, having lost 27% of their personnel, 80% of their armored fighting vehicles, 50% of their attack helicopters and 38% of their overall combat power.  This compares favorably to the ISW’s estimate of 458 casualties (the TNDM predicted 521) and 80 pieces of equipment, compared to the TNDM report of 89.  50% losses to the attack helicopter force is probably a bit overstated and could bear closer examination.

In contrast, the Ukrainians lost 6% of personnel (85 men), 2 AFVs and 6% of their combat power. 

This disparity in the loss of combat power to the two sides would have undoubtedly made another attempt to cross the river on the 12^th a non-starter, even though some sources have reported it as a two-day battle.  If these losses are indeed indicative of what really happened, the second day’s attack could only have been carried out by the 35^th Brigade’s BTG.  This would imply that not one, but two BTGs may have been wrecked in the Siverskiy Donets operation.

Run #2: While the force-to-space ratios don’t really support at two-BTG attack, it is possible that when the 74^th Mech’s BTG was rendered combat-ineffective, the 35^th’s BTG was passed through the 74^th to renew the attack.  By including both BTG’s in the Russian Order of Battle and throwing in the balance of the 120^th Artillery Brigade, we can see the impact of a rough 2:1 numerical advantage for the attacker’s side.

As it happens, even this reinforcement only yielded a combat power ratio of 1:1, which did not allow for a successful crossing of the river.  Russian casualties were somewhat lower, but still higher than the defender’s losses.  Both sides took about 7% personnel losses, but the Russian units had roughly double the personnel, so took 271 casualties as opposed to only 110 by the Ukrainians.  The Russians lost 29 AFVs to the Ukrainians’ 3, but this is deceptive as the defenders had only a small number of tanks to lose — their 3 AFV losses represented 45% of their starting force.  The bigger story is that the Russian’s lost 15% of their combat power, while the Ukrainians lost just 8%, thus ensuring the attackers would never make it across the river without significant reinforcement.

Run #3: Some sites have reported that the operation continued into a second day, so the third run was essentially the first run with a second day’s extension where the 35^th Brigade’s BTG took over the fight.  I also postulated that it would be too expensive for the Ukrainians to devote a second package of Switchblade drones to battle.  Therefore, the defenders’ combat power was weakened in comparison to the first day’s battle, despite their low losses.

After extracting the losses to the defenders and not adding the Switchblade package back in, the fresh 35^th Bde BTG replaced the broken 74^th’s BTG with exactly the same combat power.  Thus, we have a fresh second echelon committed to battle against a moderately depleted defender. 

Results:

Without their Switchblade drones, the 79^th Air Assault Brigade defenders were unable to repulse the second echelon, though the attack was only able to make 350 meters beyond the river’s edge.  In doing so, the Russians lost another 323 men, a third of their AFVs and 14% of their combat power.  The defenders lost 130 men, 2 AFVs and 1% of their combat power.  All told, in the two-day battle the Russians lost nearly 850 men, 45 AFVs, had one BTG rendered combat ineffective and barely gained a toehold on the south side of the Siverskiy Donets. 

Run #4: Clearly, a CEV advantage to the Ukrainian side would merely make the Russian defeats in Runs #1 and #2 worse, so they needn’t be explored further.  Run number 4 was run as run #3, but with a Ukrainian CEV of 1.2.

Results:

On day 1, the Russians lost 57% of their combat power and 124% of their AFVs, indicating they their armored vehicles wouldn’t have survived to the end of the day, thus the battle would have likely ceased less than 16 hours in.  After such a slaughter, it is questionable if the Russians would have tried it again the next day with the second BTG.

On day 2, the Russian second echelon managed to take the crossing site to the same depth as run #3, but lost 50% of their AFVs and 20% of their combat power in doing so.  The casualty list after two days would have totaled over a thousand Russian soldiers.  Technically, this might be called a Russian “victory,” but without a substantial exploitation force behind them, it would surely be a pyrrhic one.

Run #5: The next few runs explored the idea that the Russians not only failed to achieve the needed surprise, but were, in fact, surprised by the resistance they ran into.  Again, runs #1 & #2 were sufficiently adverse to the attacker that they needn’t be explored further.  This is a re-run of run #3 with minor surprise by the defenders.

Results:

While the 74^th’s BTG was thoroughly destroyed (41% personnel losses, 161% of AFVs and 71% of its combat power lost), interestingly, the 35^th’s BTG made the same gains and losses were almost exactly what they were in run #4.  This surprising result is because surprise degrades over time, and the second day of minor surprise essentially equates to the Ukrainian CEV of 1.2 from run #4.

Run #6: Given this, run #6 was done with substantial surprise.  Not surprisingly, the 74^th BTG was obliterated in short order, losing over 54% of its personnel, 271% of its AFVs and 115% of its combat power.  It could be scratched out of the Russian OOB after half a day’s fight.  The 35^th BTG, however, still made it across the river, albeit at some cost.

Run #7: Run 7 was done with complete surprise — not a likely situation, but one explored for completeness.  The results were much the same, with the 74^th annihilated after just a few hours, while the 35^th persisted in gaining the far bank of the Siverskiy Donets.  However, at a cost of 1/3^rd of its personnel, all of its AFVs and 35% of its combat power, the BTG would have been hors de combat until a rest and refit period were accomplished.

At this point, I ran several sensitivity exercises without using the Switchblade package from the first day of the battle, but including variations of surprise and CEV.  No amount of surprise was capable of repulsing the attack and only a Ukrainian CEV of 1.5 proved sufficient to keep the Russians on their side of the river without the use of the kamikaze UAVs.  As a large influx of combat power in some form was needed to rebuff the attack, I made a final run with the entire 79^th Air Assault Brigade in place of the Switchblades.  This did, indeed, defeat the single BTG on day 1 of the battle with losses comparable to those estimated to have actually been incurred by the Russian force.  In other words, it took a force three times the size of our estimate to successfully defeat the river crossing without extraordinary support.  This would, of course, have been advantageous for defending a day 2 attack by the 35^th BTG had it occurred, since the entire brigade would remain in place, as opposed to the Switchblade package that we posited would be too expensive to recreate for the second day’s battle.

Conclusions:

Once again, the TNDM has demonstrated that the reported results of this battle are entirely consistent with historical outcomes — nothing too unusual or particularly remarkable happened here.

Also, Russian tactical incompetence is once again the key to interpreting the results of this battle.  Had the Russians achieved the prerequisite surprise, things would have gone very differently.  A final model run with the shoe on the other foot confirms this.

Finally, the impact of a single weapon system — in this case the Switchblade kamikaze UAS — proved pivotal.  Essentially a round of ammunition, these killer drones significantly boosted the combat power of the defenders.  However, once expended, the defending units went back to their organic firepower, which was insufficient to hold the line.  This underscores the importance of a steady, sustainable supply of weapons and logistical support from NATO and other countries sympathetic to the Ukrainian cause.