 Complete the following phrase:  On 18 September 1939, in the course of the Soviet invasion of Poland, Skidzyel was the site of a pro-Soviet communist revolt against the Polish government leading to massacre of ethnic Poles by killing squads deployed by delegalized Communist Party of Western Belarus, armed with the smuggled Soviet guns soon before the invasion. The event is referred to by historians as the Skidel revolt. On 19 September, a unit of the Polish Army restored Polish control in Skidzyel, but the next day, 20 September, the town was 