The war cemetery at Kostiuchnowka was established after the bloody battle fought on 6 November 1915, when Polish legionnaires recaptured the Cegielnia hill, later called the Polish Hill, from Russian hands. The cemetery was situated next to a small chapel erected by the legionaries. Further burials were made in this cemetery in July 1916, burying here legionaries killed during the fighting with the Russians during General Brusilov's offensive. In the years of the Second Polish Republic, the area around the Polish Mountain was tidied up, and cemeteries were established in Polski Lasek, Koreshchy, Kowel, Maniewicz and Wolczeck. These cemeteries were consecrated in 1929 in the presence of the President of the Republic Ignacy Moscicki. The necropolis in Polski Lasek was renovated in 1930 by the War Graves Department, functioning within the structure of the Ministry of Public Works. During the communist period the cemetery was destroyed, but the grave fields were preserved. The cemetery chapel was destroyed during World War II - in 1943 it was destroyed by soldiers of the Ukrainian Insurgent Army (UPA). In 1996, scouts from the Zgierz Scouting and Guiding Association (ZHP) started to rebuild the cemetery. The works were financed by the Council for the Protection of Struggle and Martyrdom Sites, and were completed in 2000. The local population actively helped in rebuilding the cemetery. After the consecration ceremony of the restored necropolis, which took place on 30 September 2000, the scouts handed over the deed of care for this cemetery to young people from the local school. The rebuilt cemetery contains 32 earthen graves, framed by concrete kerbs, on which stand low concrete crosses. In the central position, a tall wooden cross with a metal Christ figure has been placed on the mass grave. The inscription on the main monument (modelled on the 'Pillars of Remembrance' found in the surrounding woods, commemorating the locations of Jozef Pilsudski's staff during the battles of 1915-1916) reads: "Here lie the Polish legionaries and soldiers of the Austro-Hungarian and Russian armies, fallen at Polish Mountain in 1915-1916. / August 2015" In 2004, the remains of 37 legionaries, exhumed from the destroyed legionary cemetery in Kołki, were buried in the cemetery. A separate obelisk was placed on their grave with the inscription: "Here rest the Polish legionaries killed at Kolki in 1915, transferred to the "Polish Forest" in 2004". In 2005, the remains of a legionnaire, exhumed from Podryż, were buried, and a monument to his memory, transferred from there, was placed on his grave, where he had been resting until then. This object was situated next to the quarters of the soldiers exhumed from Kołki. In the following years, the cemetery was under the constant care of the scouts. Since 2017, this care has been financed by the Ministry of Culture and National Heritage under the Minister's Programme "Sites of National Remembrance Abroad". In 2018, the scouts rebuilt the cemetery chapel, destroyed during the communist period. The work was funded by the Ministry of Culture and National Heritage. In 2020, four plaques were placed in the cemetery with the established 34 names of fallen legionaries. The inscription in their honour (in Polish and Ukrainian) reads: 'Pamięcy / Rycerzy Niepodległości / Legionistów ? Józef Piłsudski / Fallen / For the Rebirth of Poland / And Resting / In This Land".