This is a brief survey of what this kind of breakthrough normally means, and what seems likely given that it has happened in the near future.
Breakthrough
In a war like Ukraine/RF the front lines are difficult to move. They are mined, multiple lines of defense etc. Even when you have shaped the battlefield progress is pretty slow, as in Kherson at the moment. Except when they are not.
The breakthrough on the Kharkiv Oblast eastern front is actually the second we’ve seen Ukraine achieve. The first was further north near the reservoir, when suddenly several villages were liberated and all crossings of the reservoir were taken for a while. RF moved troops back and retook some of that territory, but the principle is the same.
If you break through the shell of the outer lines, and you do not encounter another prepared line of defense you are now in an area free of mines, free of artillery barrages and with relatively little to stop you beyond security garrisons and any hardpoints (typically supply areas or nodes where the mobile reserves exist to respond to such breakthroughs). In Ukraine, this is simplified by the fact that the civilians see Ukraine forces as liberators, not invaders, so the civilians do not become a source of difficulty (to contrast with RFs experience aound Kyiv). Also simplified by the fact that RF seems to have no reserve at all, or if they had a reserve it fled instead of fighting.
Doctrine says you devote some forces to making the breakthrough permanent, widening it and clearing it of enemy forces, fortifications, mines and such to allow logistics to flow to the attacking force. If you have any more forces, you send follow-on waves, to the limits your logistics can support.
Exploitation
With nothing much to stop you, how far can you go? There are natural limits.
Fortified Front lines
Obviously if you encounter a front fortified from earlier activities and still manned with ready troops you can not progress at the rapid speed of exploitation. Right now such lines only exist in the north where prior breakthroughs and crossings of reservoir have fortified all points near the border villages and especially near the two border crossings, including the main rail hub going south. The entire Donbas region is wide open all the way down to the pre-February borders with the DPR and LPR. Those were fortified for 8 years and would be a very strong fallback position.
Successful attempts for the enemy to establish a blocking force will also cause a barrier if held with determination and proper support from artillery etc. There are enough forces in Donbas region that it is probable they will establish a new line somewhere well before the DPR/LPR borders if given time. In the north, it is possible reinforcements will halt before being thrown away and form a line with their west flank held by the reservoir and east flank by the Russian border. For now though we see no sign of such blocking forces forming.
Natural barriers
In this war, the Russian border is a natural barrier. Crossing it would be a political act well beyond the pay grade of anybody at the point of the spear. Rivers are a pretty strong barrier but if easily forded or with intact bridges they may not stop an army, as we are seeing this morning. Something as big as the reservoir is a barrier. In this current exploitation the only major river barrier has already been crossed, so only the border is significant.
Friction
Every kilometer you move extends supply lines. Each settlement taken requires some form of security force or assistance. Every hour of effort has wear and tear on your vehicles and your soldiers. You can to some extent mitigate this effect if you can rotate troops in, having followup waves advance while early waves rest and refit and reorganize. Ukraine is attempting this, it is a lot easier since RF seems to have no organized air or artillery assets in range. But at some point, even with no resistance and a friendly population you have to stop. (for Patton in 1944 his entire force ran out of gas).
Encirclement
The image above shows the reality of “front lines”. They don’t look like the solid red or blue blobs on the maps we have been looking at. They are static and are not even as solid as the wargame above indicates, mostly troops live in nodal areas on the front and have sufficient recon assets to detect incoming enemies and respond to them, covering the vast empty spaces between troops with minefields or other things that block fast movement (a thick forest with undergrowth slows things enough that you can respond, as can an area with creeks or mud or a swamp or just a lot of hedgerows).
The big danger of a breakthrough for the victim of it is encirclement. If a second point can be breached, from the front or from a breakthrough force attacking from the rear, a chunk of troops are cut off and basically hosed unless a counterattack is coming very soon. (Some US troops in Battle of the Bulge resisted encirclement until rescued. Usually such troops eventually surrender).
This is happening to Izyum pocket right now. There is no risk of this to the RF troops in the north, they can easily retreat to fortified lines, unless they try a forward blocking force that gets cut off from a new breakthrough across a reservoir crossing (if I was in command that would worry me and I’d pull all the way back to the border, but higher command might want to hold as much ground as possible for political reasons). Mostly though the risk going forward is to the Donbas region troops, especially those who are in recently captured areas on the wrong side of the river. If they find Ukrainian forces coming from the breakthrough direction behind their lines and occupying their former front on the riverline, their only supply comes from the south, and those supply lines are already overstretched trying to support the land bridge and Kherson.
Wild Ass Guess Prediction Short Term
Barring unforeseen RF getting its act together and really mustering a potent counterattack within the next couple of days, I think the lines stabilize as follows.
1. North borders stabilize at fortified positions, with Ukraine in possession of reservoir and its crossing points, and east to the RF border.
2. East Ukraine pushes all the way to the border. Any RF troops in that area have no realistic supply options, although a fortified front similar to the north might emerge near the border crossings.
3. Ukraine consolidates gains along the highways from Kupiask to Lyman but does not push much further, preferring to ensure that the Izyum pocket is 100% screwed and actually surrenders. This slows their rapid pace to the southeast/Donbas area long enough for RF to form some kind of defensive line.
Even Wilder Ass Longer Term
RF is going to continue to have a weakness in the SE unless they pull all the way back to LPR and DPR separatist regions, although there may be other defensible lines based on artillery and air support range that are outside of what I know about. Nothing in that sector was fortified, it was captured early and was never front line, except along the river and those areas are being approached from behind.
RF north will probably hold as long as they find shelling Kharkiv worthwhile. They have easy supply, Russian air bases etc. If they are moved, it will be in a slow way, similar to Kherson offensive but without benefit of the troops being out of supply. Gut instinct is Ukraine waits till Kherson and other more promising areas resolve.
RF south is another “too much bread, not enough butter” situation. Best troops and largest concentration are on tenuous supply line and under continuous attack. Long front to defend but well fortified, but who is manning those fortifications? There is already a push to its main supply/rail hub and some of it is in artillery range, plus HIMARS ranges across the entire front.
My feeling is RF will try to hold both Donbas and Land Bridge and eventually fail at both. They might have enough force remaining to hold one or the other, but they’ll leave weak spots if they try to defend it all. If it was politically possible as commander I’d try to pull all the way back to DPR/LPR and just try to hold the land bridge if Ukraine kept pushing in the SE rather than doing the conservative thing and just ensure Izyum region is nailed down.
Comments welcome.
update
Ukraine seems to have launched an extra offensive near the north border, probably crossing the reservoir as they did a couple months back and Telegram is panicking. Should that attack prosper, revise my above WAG prediction to “all the way to the border in north and east”. I would also predict as less of a WAG that regardless of the success of that effort, there will be no blocking force or countrattack coming from Belgorod direction.
RF might still hold the area north of Kharkiv (they have a different border crossing that is strongly held) although that area is also under attack, in the “slow pushing through fortified areas” kind of way we are seeing in Kherson, with the extra difficulty of good supply.
Saturday, Sep 10, 2022 · 6:31:25 PM +00:00 · greblos
Strategic Rout?
Rout is normally a battlefield tactical term. Historically, think of a pitched battle with a left, middle and center on both sides. Left flank starts to get pushed back and waver.
In a disciplined army, the center and right will maneuver to keep the whole in place, maybe backing up or executing a maneuver that might resemble a curve or a square if the right flank also is under pressure.
In a less disciplined army, the guys in the center or right flank might not have faith in either the courage/ability of the left or the rest ability to do a difficult evolution to keep the line intact. So they say “screw it” and run away.
Even if you are winning, some portion of your troops might decide all is lost due to fog of war or a local situation and flee, and their panic might infect reinforcements, or a reserve line or similar. This was a serious problem that all armies worry about, especially when using conscripts, raw recruits or auxiliaries that might not have the expected trained/disciplined reactions to battle as veterans.
Strategic Rout
Strategic rout historically is relatively rare. This is a situation where an a entire front or even nation panics in spite of objectively having significant military power and places to reform, regroup and defend after a setback. Part of why this is rare is speed of communication. You are sitting in your castle, defending your region and the King just lost the entire flower of chivalry to enemy archers half a country away. By the time you find out about it, the situation has stabilized.
The cause is similar when it does happen though. An area not under threat or otherwise stable even if in front lines is manned by soldiers that lose faith that their position will remain secure due to actual or expected failure of the people responsible for covering their rear or flank. Executing initiative (or saving their own skin in absence of leadership) they flee where nobody pursues, yet. Puzzled enemies see empty trenchlines or castles abandoned or whatever is appropriate to the era, then follow.
We might be witnessing a strategic rout on a scale hard to imagine when the regime that sent the army is intact, where numbers are still not overwhelmingly bad, where local supply is still intact and where military logic should say Ukraine can’t push forever without hitting limits and where strong natural and man made defenses exist to fall back upon.
How much fighting is really happening, and how much is Ukraine driving as fast as they can and finding abandoned positions?
What may be new compared to history in this war is social media communications at the soldier level. RF troops seem to have little faith in their leadership, in their fellow soldiers, in any of the various branches (national guard, paratroopers, mercenaries or other “elites”). RF troops also seem to be able to complain to each other or loved ones over cell phones at will, or tweet on Telegram.
Given that environment, if you were a unit that might be cut out of supply and encircled if some other distant unit failed to hold their ground, would YOU stay in position? Especially as all reports say “everybody is running away anyway, leaders first?” Especially when you have been treated like cannon fodder, watched elites get loot while you did not get paid or rotated out of the front lines, etc?
Where do they stop running? Probably when not allowed through the border, if the incursion a few months back by Ukraine into the north is any indication. Or when they run into a disciplined force that is holding its position and tells them to stop running and get into the trenches “or else” and is willing to use force to make it happen.
This is all speculation, but really, most reports on both sides indication movement, but not actual fighting. That sounds a lot like Ukraine is trying to catch up to fleeing Russians more than pushing them out of the way.