MOSCOW — In a schoolyard in Moscow shaded by birch trees, a group of children held in their hands portraits of their ancestors who died in World War II. They were waiting to join one of this year’s Immortal Regiment marches — held across the country to honor the war dead.

“The idea is that we walk with pictures of our relatives,” said Pavel Mramornov, 11, holding a portrait of his great-great-grandfather, who died in 1944. “We carry our relatives in our hearts.”

The students’ relatives were among the 27 million Soviet soldiers and citizens estimated to have died in the war, which touched nearly every family in the country and which is still treated as a sacred era in Russia’s history.