KYIV, July 20 — The shift in how Ukraine fights its war is not about a new drone or a fresh artillery shell. It is about the structure beneath the line: the Territorial Defence Forces, a reserve corps that quietly went from a citizen experiment to a formal military branch in under a decade. Watch this space – because what started as a stopgap for a reeling army has become a model that at least one NATO neighbour is already copying.
After Ukraine’s military setbacks in Crimea and the Donbas in 2014, civilians took matters into their own hands. Volunteers formed militias known as Volunteer Battalions.
The Ministry of Defence organised some of those into Territorial Defence Battalions, and those units are credited with holding the line long enough for the regular military to pull itself together. That ad‑hoc system changed in late 2014: the battalions were transferred into mechanised infantry brigades, and a new territorial‑defence structure took shape. From 2015 until 2021 the Territorial Defence Forces existed in semi‑organised forms.
Then came the law. President Volodymyr Zelensky signed it on 29 July 2021, after the Verkhovna Rada approved it on 16 July.
The bill had been introduced on 25 May that same year. On 1 January 2022, the TDF became a unified corps – a separate branch of the Armed Forces of Ukraine. Planned volunteer numbers were increased from 1.5 million to 2 million on 11 February 2022, a little over a week before the full‑scale invasion.
Activation and the civilian wave
When Russian forces moved in February 2022, the TDF activated. The surge was immediate. By March 2022 more than 100,000 civilians had volunteered – a number that dwarfed the peacetime reserve target.
The force is built on a core of part‑time reservists, often former combat veterans, and in wartime can be expanded with local civilian volunteers under mass mobilisation. That mix of professional backbone and citizen surge is what’s changing the calculus for Ukraine’s defensive depth.
Foreign volunteers also joined. The International Legion of Territorial Defence of Ukraine, a formation of non‑Ukrainian fighters, operated under the TDF until 2023, when the arrangement shifted.
A model for Poland
The trend underneath is that the TDF is no longer just Ukraine’s story. Poland used the Ukrainian model to build its own territorial‑defence force starting in 2015. That is a rare case of a reserve system
