In the military section of the Catholic cemetery, a total of around 1,000 dead prisoners of the Kosachiv camp, where in 1919. Ukrainians held Polish and Soviet prisoners of war. Initially there were graves without crosses and mass graves with inscriptions: "Here lie 70 internees of unknown name" or "Here lie internees of unknown name". These inscriptions were made in pencil by one of the internees assigned to bury the dead. In the 20 years between the wars, the Polish Ladies' Committee decided to collect contributions and display a common gravestone for all the dead. This objective was realised in 1922 according to a design by the painter Stanisław Leopold Maksymilian Daczyński. The memorial is of reinforced concrete, consisting of two elements: a wall with a higher central section and a cross on a three-tier base, with a small cast-iron plaque bearing the inscription: "To the victims of Kosachevo Compatriots"; the dates "1918-1919" are engraved on the cross arm of the cross. The central part of the reinforced concrete wall was filled with white marble slabs bearing the names of the dead. Nameless concrete crosses were placed around the memorial.

After 1946, the marble slabs with the names of the dead were destroyed.

The monument was renovated in 1995 through the efforts of the Centre for Polish Cultural Heritage Abroad, operating at the "Polish Community"; the renovation was financially supported by the Council for the Protection of Remembrance of Struggle and Martyrdom. Unfortunately, already after the renovation, the monument was painted over with some inscriptions. In 2023, the Armenian Foundation carried out the restoration of the monument. The work was carried out within the framework of a task subsidised by the programme of the Ministry of Culture and National Heritage 'Sites of National Remembrance Abroad'.