On 13 August 1949, in Užpelkiai Forest in northern Lithuania, on the border of the Grinkiškis and Baisogala rural districts in Radviliškis County, a battle by Lithuanian partisans that had a significant impact on the history of the Prisikėlimas (Resurrection) district took place. The leaders of the Lietuvos Laisvės Kovos Sąjūdis (Movement for the Struggle for Lithuania’s Freedom) operated in this district. Based on the approach of modern conflict archaeology, the authors of the article, helped by volunteers, determined the location of the Battle of Užpelkiai Forest (in the Grinkiškis rural district, Radviliškis County), and collected a lot of new archaeological and historical data, in order to reconstruct the progress of the attack by MGB (Ministry of State Security) troops and the partisan defence. By referring to complex research results, the article gives the surnames and duties in the organisation of all the partisans who participated, as well as the circumstances and progress of the battle. It shows the importance of the Battle of Užpelkiai Forest to the Lietuvos Laisvės Kovos Sąjūdis in 1949–1950. The case study of field research into the battle in the partisan war shows how complex historical and archaeological research complements the picture of the partisan war with facts and artefacts, clarifies or denies old interpretations, and leads us to new ones.