WARNING: GRAPHIC IMAGES: Between 1943 and 1945, units of the Ukrainian Insurgent Army killed up to 100,000 Poles in Wołyń and eastern Galicia, former Polish territories now in western Ukraine. At its height, the butchery saw as many as 8,000, including women, children and the elderly, murdered in just one day. It remains one of the darkest chapters in the two nations' histories.
The armoured warriors who use middleage styles and tactics competed in sword and shield, long-sword, polearm and melee events, traditionally called buhurts.
According to the Ukrainian Embassy, around 7,837 people voted in Warsaw and in the consulates in Kraków, Gdańsk and Lublin.
Prime Minister Mateusz Morawiecki wrote on Twitter on Thursday that Poland owes remembrance to Poles who were murdered in Huta Pieniacka (today western Ukraine) by Ukrainians from the Ukrainian Insurgent Army (UPA), a Nazi SS division and other barbaric units.
Lithuanian President Dalia Grybauskaite on Thursday afternoon started her two-day visit to Poland. She was officially welcomed by Polish President Andrzej Duda in the courtyard of the Presidential Palace in Warsaw.
Poland has over 200 soldiers stationed in Romania, which form part of a NATO division defending south-east Europe.
Polish Deputy Foreign Minister Bartosz Cichocki declared on Monday that Poland will cooperate with France and Germany to de-escalate tension in the Sea of Azov and for Russia's return to observing international law.
During a telephone conversation with President Andrzej Duda, the President of Ukraine Petro Poroshenko described the current situation in the Sea of Azov as serious and dangerous for Ukraine, Polish president's aide Krzysztof Szczerski has said.
The best musicians from Poland and Ukraine, with the support of the Adam Mickiewicz Institute, will create an orchestra of entertainment.
Germany and Poland see the importance of stability in Ukraine, also in the context of the Nord Stream 2 gas pipeline, PM Mateusz Morawiecki and German Chancellor Angela Merkel said after Friday talks in Warsaw.