In a rapidly changing global landscape where the belief in eternal peace has been challenged, Europe today prioritizes national defence and the reconstruction of both territorial and total defences to achieve resilience and resistance against external hostile state actors. Ukraine began implementing a Resistance Operating Concept during the Russian occupation of Crimea in 2014, subsequently refining it. However, there is currently a lack of studies on whether theconcept has been successful. This study aims to contribute to the existing research on resilience and resistance from a Ukrainian perspective. Specifically, it seeks to explain why Ukrainian territorial defence forces (TDF) succeeded against a highly qualified and superior adversary during the full-scale Russian invasion of Ukraine in 2022. This study follows an outcome-explaining method and employs Liddell Hart's Strategy of the Indirect Approach supported by Biddle and Kilcullen. The study found that by deploying TDF units early and using them in a flexible, adaptable and unconventional manner through mission-type tactics, Russian resources were tied up, further advances were delayed, logistics to lead assault units were impeded, allowing time for Ukrainian conventional units to mobilize and conduct counterattacks; ultimately preventing Russia from capturing Kyiv and quickly ending the war.