Short answers, pulled from the story.
Joseph Stalin ordered the creation of partisan detachments on the 3rd of July 1941 through a radio broadcast declaring war on Nazi Germany. Directives from the Soviet People's Commissaries Council issued on the 29th of July 1941 called for diversionist groups to form in German-occupied territories.
Panteleimon Ponomarenko established the Central Headquarters of the Partisan Movement under Stavka in spring 1942. Kliment Voroshilov initially commanded this body before handing operational control to Ponomarenko.
Operation Rails War ran from August 3 to the 15th of September 1943 involving over 100,000 partisan fighters across multiple regions. More than 230,000 rails were destroyed along with numerous bridges trains and other railroad infrastructure during this major campaign.
German anti-partisan actions killed an estimated 345,000 people mostly civilians in Belarus according to historian Christian Gerlach. Hostage operations included preliminary arrests post-attack retaliation actions and compulsory watch-groups deployed on vulnerable sites.
State Duma established Partisans and Underground Fighters Day in March 2009 while President Dmitry Medvedev made it law on the 11th of April 2009. The holiday celebrates June 29 since 2010 marking the anniversary of the 1941 directive Council People's Commissars declaring intention create partisan detachments.