["The Fourth Year in a Row," sometimes called "Four Years," by the great Russian poet-singer Bulat Okudzhava, who had himself fought in the war.]
I'm reckoning World War II from Russia's perspective, beginning with the Nazi invasion on June 22, 1941 (as it happens, the Nazis bombed Kiev on that first day of the war) and ending with the Russian V-E Day, May 9, 1945. Naturally others, whether Americans, Poles, or Chinese, will give you different lengths. I'm also reckoning the Russo-Ukrainian war from the February 24, 2022 full-scale invasion; one could also go back to 2014, the date of the Russian actions in the Donbass and the Russian invasion and annexation of Crimea.