Original sentence: Memories of Operation Wisła remain another scar in the complex, often troubled 20th-century relations between the Ukrainian and Polish peoples, alongside the Massacre of Poles in Volhynia by the Ukrainian Insurgent Army during the Second World War in the wake of the interwar oppression of the Ukrainians in the Polish controlled territories that followed the brutal fights in Galicia in 1918-1919
Edited sentence: Memories of Operation Wisła remain another scar in the complex, often troubled 20th-century relations between the Ukrainian and Polish peoples, alongside the Massacre of Poles in Volhynia by the Ukrainian Insurgent Army during the Second World War in the wake of the interwar oppression of the Ukrainians in the Polish controlled territories that followed the brutal suppression of the post-World War I Ukrainian drive for self-determination in Galicia