The Kherson Counter-Offensive has been so much talked about in recent weeks as to have acquired the resonance of an historical conflict that has already taken place. Now, at last, it is a reality. Its eventual purpose is to retake Kherson, the only Ukrainian provincial capital in Russian hands and the gateway to Odesa, representing the danger of Russia converting Ukraine into a land-locked country. A further motive is to show the West that its military support is a worthwhile investment, as we enter a winter of fuel poverty, by gaining a significant victory.

Ukraine has been exceptionally successful in keeping its movements and objectives secret. One Western commentator this week remarked ruefully that we know more about the Russians’ dispositions than the Ukrainians’. So, piecing together information from a variety of open sources to try to get an overall picture of events carries a large caveat; but, so far as can be ascertained, the situation is as follows.

Ukraine opened its counter-offensive with a three-pronged attack: the southernmost from Mikolaiv directly towards Kherson city; the second in the rural north-west; and the third from the north. These two latter attacks appear to have converged, trapping enemy units and gaining the surrender of some forces from the Donetsk pseudo-republic, as well as Russian troops. Contrary to the Western media focus on Kherson city, the fiercest fighting has been in the north of the Kherson oblast, in the area furthest removed from the capital, centred on Velyka Kostromka. The very intelligible purpose of this northern offensive is to win a road to Nova Kokhovka, with its dam, controlling the water supply to occupied Crimea.

This is not a textbook counter-offensive, since the Ukrainians have committed approximately 20,000 troops to attack an equivalent number of Russians, when military doctrine demands a three-to-one superiority (some cautious commanders say five-to-one) for offensive operations. Ukraine does not have that kind of superiority, so all the signs are that it is imaginatively creating a new style of pragmatic offensive. Any thought of Ukrainian armour and infantry racing to Kherson city and storming it should be dismissed. The Ukrainians do not want to kill their own citizens in Kherson or destroy yet another of their cities. Their plan is to isolate Kherson and force the surrender of the garrison or its retreat across the Dnipro river.

The Dnipro is key to the military situation. In a series of “shaping operations”, the Ukrainians have progressively destroyed all but the pedestrian bridges across the river. The Antonivskiy, Dariivskiy, Kakhovskiy bridges, including the railway crossing (vital for Russian military movements), and the Dimitryivskiy bridge across the Ingulets river have all been put out of commission. By Monday, the Russians’ pontoon bridges and slow-moving barge ferries had largely been destroyed. Only pedestrian bridges remain and that is no coincidence: some Russians may escape, in the event of a collapse, but they will not be able to take their equipment with them.

The situation for the Russians is beyond dramatic. Some 20,000 soldiers who cannot be resupplied or reinforced (except by riflemen) are facing a counter-offensive along a 160km front. Before them is a hostile country and its advancing, vengeful army; behind them a broad and impassable river. Fighting with one’s back to a river is the ultimate military nightmare: as long ago as 312, it did for Maxentius at the Battle of the Milvian Bridge – indeed, Constantine employed exactly the same tactics as the Ukrainians.

The other key factor is morale. When the Ukrainians began, deliberately, to become slack-jawed about a Kherson counter-offensive weeks ago, Vladimir Putin doubled his forces in Kherson oblast from 15 battalion tactical groups to more than 30. In Kherson city these are under the 49th Combined Arms Army of the Southern Military District. Further north, where the fighting is already fiercest, the defenders are principally drawn from the 35th Combined Arms Army of the Eastern Military District, which includes the butchers of Bucha, who will not relish the prospect of being captured by the Ukrainians.

When these dispositions became known, a month ago, military analysts began to canvass the problems of integrating the 49th and 35th Combined Arms Armies, from different military districts, into a coherent fighting force. But the reality is even more chaotic: the Russian forces in the Kherson oblast are a hotch-potch of reconstituted fragments of units and isolated forces as disparate as the 22nd Army Corps of the Black Sea Fleet, the 76th Guards Air Assault Division and Rosgvardia (Russian National Guard). Command and control is notoriously incompetent.

Then there is the sudden return of the Ukrainian air force, which appears to be flying missions over Kherson unchallenged, since recent Ukrainian attacks on Crimea forced the Russians to withdraw their aircraft too far back to be able to respond in time to raids. Russian propaganda boasts of the volunteer 3rd Army Corps, 40,000 strong, newly raised and armed with Russia’s most state-of-the-art weaponry, including BMP-3 infantry fighting vehicles, T-80BVM and T-90M tanks, and the latest models of the AK-12 assault rifle. For the last ten days they have been deploying from their training base at Nizhny Novogorod towards Ukraine.

But that is small consolation to their comrades in Kherson, since they appear to be deploying on the Donestsk front. That is inevitable: how could they get their modern tanks and vehicles across the Dnipro to succour the Kherson garrison? They could help create a distraction by adding impetus to the snail-slow progress of the Russian advance on the Donetsk front, where Sloviansk and Kramatorsk remain untaken, more than six months into the war. But analysts believe that, despite its modern equipment, the 3rd Army Corps is full of men with no military experience, many of them old for military service.

Ukraine is advancing slowly and commentators pointed out in the early days that the first villages to fall – Arkhanhel’s’ke, Novodmytrivka, Pravdyne – were very close to the previous front line. There is great caution among Western commentators, a palpable scepticism about the success of the counteroffensive. But there is now evidence of deeper and faster penetration. If there is any kind of collapse among Russian forces in the north of the oblast, the whole battle could roll down very fast to Nova Kakhovka and the vicinity of Kherson city.

Ukraine has only been able to mount a counter-offensive because of its improved artillery capability due to Western support. It has used that capacity to destroy all lines of communication between the rest of the theatre of war and 20,000 Russian troops trapped on a shrinking island surrounded by water or a hostile army, with no means of resupply. If, as winter approaches, they either abandon their equipment and flee, or are surrounded in a miniature Stalingrad of their own making, the humiliation for Russia will be intense and the whole shape of the Ukrainian war will change.