Let’s have a look at an arbitrarily selected, quite representative area of Eastern Ukraine:
The first satellite imagery screenshot shows the larger area, the lower ones shows a smaller area from the former’s centre. Some measurements of distances are included, and a scale is on bottom right each.
The agricultural areas are divided into rather large sections, as is typical of Eastern Europe where the socialist economies of the Cold War era attempted to run agriculture like factories in kolkhoz and in Soviet Union the even bigger sovkhoz. The fields are divided by treelines as seen well in the lower screenshot and also on many, many war videos from Ukraine. These treelines likely serve to reduce soil erosion by wind.
These treelines provide at least a partial interruption of lines of sight from late spring to late autumn. The biggest single field section in this area was rectangular, 1.6 x 1.0 km large with a measured diagonal of 1.9 km. All those portable ATGMs of (published) 2 km range are thus fully sufficient for line of sight surface-to-surface engagements in this terrain. Helicopters could in theory make use of longer-ranged ATGMs, provided they survive over the battlefield.
The terrain is similar to the bocage type of terrain in Normandy ’44 (link), but without the feature of built-in ramparts in the hedgerows.
Such terrain can be considered advantageous to defenders, but it can also be very advantageous to a well-equipped attacker. The line of sight interruptions isolate the battlefield into cells, and an attacker can presumably focus on a few cells (not just one, for else artillery would focus on too tightly packed attackers) at a time and overwhelm the isolated defenders there.
Defenders cannot survive on the open fields if the attackers have a bird’s view of the battlefield. All defenders in the fields could easily be targeted by indirect fires, depending on vegetation even by snipers. So defenders have to hide in the treelines, and in hope of surviving artillery they might dig in. Such prepared positions could be found rather easily and would then allow an accurate bombardment provided the attacker has this in his repertoire. Other treeline sections might be sprayed with fragments by artillery just in case there are hidden but not dug-in defenders. You only need multispectral smoke to conceal an attack route to the left and right flank if the treelines are not concealing enough after being shredded by some HE shelling. Any defenders who temporarily leave their position to dodge the shelling would have to be detected by the bird’s view asset and be subjected to accurate responsive fires, for else they might be back to their dug-in positions before the ground assault arrives. The alternative is a longer-lasting suppressive fires shelling to prevent the defenders from returning in time.
And then you can push with tracked armoured vehicles through one field section to the next treeline, followed by another artillery-supported push through the next section, then another artillery-supported push to break into a village, followed by dismounted action. Use multiple axes of advance to encircle defenders.
So given some AFVs (tracked APCs should suffice), plenty artillery HE shells, ability to accurately shoot with artillery on short notice, a bird’s view asset with real-time communication and some capable infantry you should be able to advance fairly well in such a terrain IF you can “synchronise” what you have in a way to gain combined arms benefits. And this is where you need a lot of training – training that you won’t get in the typical Western army training areas, either.
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The terrain also offers opportunities for a very low force density elastic defence. You just need some small infantry teams with scoped rifles, light machineguns, radios, thermal vision and possibly 2 km laser rangefinders to defend most of those field sections. They could make good use of some sensors (including simple tin can-connected tripwires) for security along the tree lines.
The attackers might overcome them, but the defender’s losses would be small due to the small team sizes and the attacker could be hit with area artillery fires on the section even if the attacked team fails to give targeting information for accurate artillery fires. Some non-line of sight missiles and loitering munitions could be used to engage AFVs in a large radius.
Any lost section could be regained by either the described systematic synchronised kind of (counter)attack or by trying to sneak with infantry sections along the treelines. An advance through (multispectral) smoke clouds would also be possible, but hardly anyone has that much multispectral smoke to spare.
Two capable but not very capable opposing forces might be locked into an attack-counterattack mess in such a terrain. Whether attackers or defenders suffer more depends in my opinion on how they attack and with what, and how they defend and with what. It’s about training (especially for the attackers), but also about hardware.
What I saw so far in OSINT does indicate that the typical attack in Eastern Ukraine involves a very small (platoon-sized) assault with overwatch firepower but little smoke and no tight synchronisation of artillery and advance. The Soviets meant to advance 300…400 m behind an artillery barrage. I have not seen any indication that either side uses such tactics, despite improved accuracy of the artillery (which would permit to advance 150…200 m behind the impacts depending on the munition used).