The Lviv pogroms were the consecutive massacres of Jews living in the city of Lwów (now Lviv, Ukraine), perpetrated by Ukrainian nationalists from 30 June to 2 July 1941, and from 25 to 29 July 1941, during the Wehrmacht's attack on Soviet-occupied eastern Poland in World War II. The German historian Peter Longerich and the Holocaust Encyclopedia estimate that the first pogrom cost at least 4,000 lives. It was followed by the additional 2,500 to 3,000 arrests and executions in subsequent Einsatzgruppe killings, and culminated in the so-called "Petlura Days" massacre of more than 2,000 Jews, all killed in a one-month span. Prior to the 1939 invasion of Poland by Nazi Germany and the Soviet Union and the ensuing Holocaust in Europe, the city of Lviv had the third-largest Jewish population in