Complex sentence: Partisan activity was singularly unsuccessful in Estonia due to the general resistance of the population to the Soviet regime that the partisans represented and the majority of partisans sent in by the Soviets were quickly picked up by the local Estonian militias.
Split into simpler sentences: Partisan activity was singularly unsuccessful in Estonia due to the general resistance of the population to the Soviet regime that the partisans represented. The majority of partisans sent in by the Soviets were quickly picked up by the local Estonian militias.