Hardly any other country marks the end of World War II with the same fanfare and fervor as Russia, for which the victory over Nazi Germany 80 years ago remains a source of immense pride and a defining moment of history.

Victory Day, celebrated on May 9, is Russia’s most important secular holiday, reflecting its wartime sacrifice. But it’s also used by the Kremlin to bolster patriotism and regain the superpower prestige it lost when the Soviet Union collapsed in 1991.

President Vladimir Putin, who has ruled Russia for 25 of those 80 years, has turned Victory Day into a key pillar of his tenure and has tried to use it to justify his 3-year-old invasion of Ukraine.

He has also sought to underline the failure of Western efforts to isolate Moscow by inviting Chinese President Xi Jinping and other leaders to the festivities, which this year have been overshadowed by reports of Ukrainian drone attacks targeting Moscow and severe disruptions at the capital’s airports, as well as cellphone internet outages.

A look at why Victory Day is so important for Russia and Putin:

The Soviet sacrifice of World War II

The Soviet Union lost a staggering 27 million people in what it calls the Great Patriotic War from 1941-45. That sacrifice left a deep scar in the national psyche.

Nazi Germany invaded the Soviet Union on June 22, 1941, and quickly overran the western part of the country. They got as close as 30 kilometers (under 19 miles) from Moscow by October of that year, but the Red Army rebounded and routed the invaders.

Soviet troops dealt crushing defeats to Germany in 1943 in Stalingrad and Kursk. and then drove the Nazi forces back across the western Soviet Union all the way to Berlin.

Putin has noted that every seventh Soviet citizen was killed, while the United Kingdom lost one out of every 127 and the United States one out of 320.

“The Soviet Union and the Red Army, no matter what anyone is trying to prove today, made the main and crucial contribution to the defeat of Nazism,” Putin wrote in 2020.

A Putin family story from World War II

Putin is deeply emotional to the history of World War II, saying “we will always remember the high price the Soviet people paid for the victory.”

He often invokes stories from his parents, Vladimir and Maria, in the war, and the death of his 2-year-old brother, Viktor, known as “Vitya,” during the 2 1/2-year Nazi siege of his home of Leningrad, now called St. Petersburg.

”It was the place where my mother miraculously managed to survive,” Putin wrote. “My father, despite being exempt from active duty, volunteered to defend his hometown.”

He also recalled in a magazine article how his father talked about a scouting mission behind Nazi lines when his comrades were killed and he survived by hiding in a swamp and breathing through a reed while German soldiers walked a few steps away.

Putin’s father was badly wounded. After leaving the hospital, he walked home on crutches to see morgue workers taking his wife’s body away for burial.

“He came up to her and it seemed to him that she was breathing, and he said to the orderlies, ‘She’s still alive!’” Putin’s father recounted to his son.

The morgue workers replied, “She’ll die on the way, she won’t survive.” But Putin said his father pushed them away with crutches and forced them to carry her back to their apartment.

World War II’s role in Kremlin policies

Putin’s emphasis on World War II history reflects not only his desire to showcase Russia’s military might but also his effort to rally the country behind his agenda.

World War II is a rare event in the nation’s divisive history under Communist rule that is revered by all political groups, and the Kremlin has used that sentiment to encourage national pride and underline Russia’s position as a global power.

Victory Day parades are a massive show of its armed forces, with thousands of troops and scores of heavy equipment, including mobile launchers carrying nuclear-capable intercontinental ballistic missiles, rolling across Red Square, and flyovers of dozens of warplanes. Military parades, fireworks and other festivities are held in cities across the country.

Authorities also encourage May 9 demonstrations featuring what is known as the “Immortal Regiment,” in which people carry photos of relatives who fought in World War II. Putin joined those rallies for several years, carrying a picture of his father.

Using World War II to justify the invasion of Ukraine

When Russia launched its full-scale invasion of Ukraine on Feb. 24, 2022, Putin declared it was aimed at the “demilitarization” and “denazification” of its neighbor, falsely alleging that neo-Nazi groups were shaping Ukraine’s politics under President Volodymyr Zelenskyy, who is Jewish. The claims were vehemently dismissed by Kyiv and its Western allies.

Putin tried to cast Ukraine’s veneration of some of its nationalist leaders who cooperated with the Nazis in World War II as a sign of Kyiv’s purported Nazi sympathies. He regularly made references to Ukrainian nationalist figures such as Stepan Bandera, who was killed by a Soviet spy in Munich in 1959, as an underlying justification for the Russian military action in Ukraine.

“The Kremlin has mixed those issues and used the victory over Nazi Germany as a foundation for building anti-Ukrainian narratives,” said political analyst Nikolai Petrov. “In Putin’s mind and in the Kremlin’s plans, the victory over Nazis rhymes with the victory over the Ukrainian neo-Nazism as they put it.”