- Service ensign · official · carried by Ground Forces
- State affiliation · Ukraine
- Vigil category device · not official insignia
Identity provenance
Service ensign: Ensign of the Ukrainian Ground Forces — carried by Ground Forces, not issued to this record. The service ensign of the Ground Forces. The design itself is excluded from copyright by Article 8 of Ukraine’s Law on Copyright and Related Rights, which names symbols and signs of government authorities, the Armed Forces of Ukraine and other military formations. The file shipped is the Wikimedia Commons SVG "Ensign of the Ukrainian Ground Forces.svg", released under PD-UAexMilitary / PD-UA-exempt on that basis, so no attribution or share-alike obligation attaches. Optimised for web display; geometry unaltered.
State affiliation: Ukraine.
The smaller square mark is a Vigil category device, drawn from this record’s own domain, echelon and role — not an official insignia.
In brief
Army corps stood up in Ukraine's 2025 corps reform around the 3rd Separate Assault Brigade; it ran Operation Vivaldi in the Lyman sector in 2026.
- Scope
- Structure, role, lineage and links. 5 subordinate records published.
- Subordination
- Subordination confirmed
- Sources
- 6 on the record
- Record state
- Partial
- Broad area of activity
- The Borova–Lyman sector of the eastern front since June 2025, by the corps' own statement; exact boundaries are not publicly asserted here.
- Notable history
- Stood up in 2025 in Ukraine's shift from brigade-centric command to army corps, built around the 3rd Separate Assault Brigade's command cadre, and among the first of the new corps to be publicly presented. Its composition is only partly public — member brigades carry graded subordination on their own records. Public compilation records the 60th Mechanized Brigade joining in July 2025 and the 53rd, 63rd and 125th in August 2025; those four are drawn under the corps from that compilation and graded reported, no official order having been read. By its own account the corps took over the Borova–Lyman sector in June 2025, and between late May and mid-October 2026 it ran Operation Vivaldi there in four announced phases, with its own brigades and formations it calls attached — the 66th Mechanized Brigade, Special Operations Forces, Defence Intelligence's Artan unit and the Border Guard. The 66th's commander calls his brigade subordinate to the corps; the others' relationship is published only as "attached". In October 2026 the corps' commander moved to command the Centre grouping of forces and a former 60th Brigade commander took the corps.
- Strengths
- Inherits the 3rd Assault Brigade's recruitment brand, training pipeline and staff culture; a purpose-built corps staff rather than an improvised grouping. Operation Vivaldi is the first public case in which the corps can be seen directing several brigades and attached units on one plan — on its own account, with deep strikes, counter-drone measures and concealment preceding the ground advance.
- Limitations
- A new structure with a short institutional track record; public information on composition and boundaries is partial and contested. Almost everything published about how it ran Vivaldi is its own account, from a formation unusually practised at publicity, and the methods it describes have not been shown to transfer to other corps.
Subordinate formations
3rd Separate Assault BrigadeBrigade · subordination reported60th Mechanized BrigadeBrigade · subordination reported53rd Mechanized BrigadeBrigade · subordination reported63rd Mechanized BrigadeBrigade · subordination reported125th Heavy Mechanized BrigadeBrigade · subordination reportedRows are layout only — position and order carry no hierarchy, importance, sequence or strength. Every record shown is an immediate subordinate of the selected organisation.
Related organisations
- KRAKEN 1654 Disputed relationship · as of 2026-09-15 · low confidence
What is disputed: the unit's current formal subordination. Later public reporting associates Kraken with the 3rd Army Corps, and the corps itself, announcing Operation Vivaldi on 15 September 2026, listed KRAKEN among its own units in that operation, while this atlas carries it under the intelligence-linked grouping on the strength of its documented origin. A formation's own list establishes participation, not an order of subordination, so neither placement is asserted as current and the unit is not reassigned until an order or a defence-ministry statement is read.
- 66th Mechanized Brigade Holds operational control of · as of 2026-10-14 · moderate confidence
Two Ukrainian statements, worded differently. The corps, announcing Operation Vivaldi on 15 September 2026, lists the 66th among the formations attached to it; the brigade's commander, interviewed by Ukrainska Pravda on 14 October, calls it a non-native brigade subordinate to the corps. Neither names a doctrinal level, so the authority is unspecified, and neither dates the arrangement. Recorded as a command arrangement over the brigade's own tree, not as membership of the corps.
Lineage & institutional history
Related locations
Lyman: The corps says it took over the Borova–Lyman sector from June 2025 and ran Operation Vivaldi there from late May to mid-October 2026. No boundary or current disposition is authored.
Dated structural changes
2026-10-19 Command change Andriy Biletskyi, the corps' commander and since 26 August 2026 also commander of the Centre grouping of forces, said on 19 October that the corps had completed Operation Vivaldi and that Dmytro Rohoziuk, formerly commander of the 60th Mechanized Brigade, takes command of the corps.
2025-06 Posture change The corps' deputy chief of staff said in June 2026 that the corps began deploying into the Borova–Lyman zone on 4 June 2025, a sector of more than 150 kilometres, and that Russian advances there of about 70 square kilometres a month stopped under its command. The sector and the date are the corps' statements; the figures are not independently checked.
Campaigns
Campaigns naming this organisation as a participant. The campaign record owns the relationship and grades it; this list is computed.
- The eastern attritional campaign Opposing force · Since April 2022 · moderate confidence · as of 2026-10
Recorded as a formation the module publishes and that is consistently associated with the eastern axis in open reporting. By its own account it has held the Borova–Lyman sector since June 2025, and it ran Operation Vivaldi there in 2026. No position is stated.
Key events
Operation Vivaldi retakes ground north of Lyman
Ukraine's 3rd Army Corps disclosed on 15 September 2026 an operation it named Vivaldi, after The Four Seasons, which it had run in secret in the Lyman sector since late May. It announced four phases between 15 September and 14 October and said on 19 October the operation was complete, its line on the Chornyi Zherebets river. The corps claims 277 km² and 16 settlements — nine retaken from occupation, seven cleared of infiltration. Independent mapping is lower and lags: the Institute for the Study of War found at least 147 km² around Lyman newly visible in its September mapping, and DeepState confirmed named villages phase by phase. The corps says it struck Russian logistics and drone units deep in the rear before its armour moved; ISW assessed that Ukraine likely neutralised Russian drone defences north of Lyman before the third phase. On 9 October ISW assessed that the operation had defeated the northern arm of a Russian attempt to envelop Sloviansk and Kramatorsk, which it called an operational failure for Russia.
Quick actions
System access
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Assessed as of — 2026-10 Last reviewed — 2026-10-20
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