January Uprising
During the November Uprising and the January Uprising the town's inhabitants took part in the struggles against Imperial Russia. After the massacres of Polish protesters committed by the Russians in Warsaw in 1861, Polish processions and clashes with Russian soldiers took place in Sejny. The Sejny County was one of the counties in which the insurgent unit of operated during the January Uprising in 1863. Sejny was one of the sites of Russian executions of Polish insurgents during the January Uprising. There is a memorial at the place of the executions.