After the German invasion of the Soviet Union in 1941 her father, who had been the chairman of the district committee, was sent to the warfront while Darya and her mother moved to Novo-Andreyevka to live with her grandmother.

[2] When the Germans occupied her village, Dyachenko joined the resistance movement after meeting with Parfentiy Grechanyy, the leader of the Komosmol organization "Partisan spark".

Each cell was composed of five people, and after obtaining typewriters and radios they summarized Sovinformburo broadcasts on paper and spread out the messages via leaflets.

[2][3] The partisans collected armaments and trained in the use of grenades and rifles before they began engaging in sabotage.

On one mission the cell led by Dyachenko derailed a train carrying German soldiers and their supplies.