December 3 was chosen because on this day in 1966 the Soviet Union celebrated the 25th anniversary of the victory over Nazi troops in the Battle of Moscow. The remains of an unknown soldier were transferred from a mass grave in the city suburbs and entombed near the Kremlin wall. On May 8, 1967, a memorial with an eternal flame was opened at the site, which is now known as the Tomb of the Unknown Soldier.

This year’s celebrations will be held at Moscow’s major WWII memorial on Poklonnaya Hill, and also in the weapon-making city of Tula and at the museum of the Battle of Borodino – the turning point in the 1812 campaign against Napoleon.

The initiative to make the day a national holiday belongs to members of the so-called ‘search units’ – a mass amateur movement of people who look for unmarked graves with remains of Russian soldiers, try to establish the names of the fallen, and put the remains to rest with all due ceremonies and procedures.

The activists first voiced their idea at the meeting with the head of Russian Presidential Administration Sergey Ivanov in September this year. They said that though there was already one similar holiday – the Day of Heroes marked on December 9 - the country has enough unnamed heroes to have a separate tribute just for them.

Ivanov agreed, and in October all four parties represented in the State Duma together drafted a bill that got its final approval by as early as the end of the month.

In 2014 alone, search activists together with special units of the Defense Ministry discovered the remains of about 14,000 Soviet Army servicemen and managed to establish the names of only about 1,000 of them.

The search movement and state structures together launched a unified database of WWII military archives, and in five years they managed to name about 800,000 soldiers who had been considered missing in action, and were buried in unmarked graves.