It's a cornerstone of the Russian political calendar.

9 May marks Victory Day when Russia celebrates the day Soviet forces took control of Berlin, ending what Russia calls the Great Patriotic War and what we better know as the Second World War.

The defeat of Nazi Germany still rings through the years as a moment of pride and admiration.

"We, the undersigned, acting by authority of the German High Command, hereby surrender unconditionally to the Supreme Commander, Allied Expeditionary Force and simultaneously to the Soviet High Command all forces on land, sea, and in the air who are at this date under German control".

So went the opening lines of the Act of Military Surrender signed by the German High Command in Rheims in 1945.

The Soviet Union, whose demise so rankles with Russian President Vladimir Putin, lost 27 million people in the Second World War, more than any other country.

Jet fighters from the letter 'Z' in support of Russia's military during Victory Day rehearsals in Moscow

The Russian President has made no secret of the fact that he believes the West has actively tried to revise the history of the war in order to diminish the Soviet victory.

"This year's Victory Day parade in Moscow will be marked with even more vigour and symbolism"

The commemoration brings a full-scale military parade in Red Square and allows Russia’s President to invoke the glories of Soviet might and determination.

This year the event will be marked in Moscow with even more vigour and symbolism than usual.

Historically, Victory Day had been a more muted affair, but from the mid 1990’s President Boris Yeltsin used the date to display Russian military hardware and hark back to previous glories.

That was a tradition President Putin was happy to continue, with a huge military parade in Red Square.

Russian military vehicles in Red Square yesterday during a rehearsal for the Victory Day parade marking the 77th anniversary of the victory over Nazi Germany in World War II

The event is all about showing pride and strength – two things which Vladimir Putin is keen to do at every opportunity.

In recent days Kremlin spokesperson Dmitry Peskov has said the "significance of this holiday cannot be overestimated."

He also suggested that the day would not be overshadowed by the ongoing events in Ukraine, but the war will inevitably loom large.

Much has been made of how Mr Putin wanted to be able to declare victory in Ukraine on 9 May, celebrating the defeat of Nazi Germany with his recently stated aim of "de-Nazifying" Ukraine.

But as with so much of what Russia wanted from this war, it hasn't quite gone to plan.

The initial belief in the Kremlin that it would all be over within days has not come to pass.

The reframed belief that a changed military strategy, moving from capturing all of Ukraine to capturing just the east of the country, has not gone to plan either.

All of this means that any Russian plan to use 9 May as a full stop in this war will now have to be redrawn, instead marking an inflection point and a rallying cry for what Moscow calls the "special military operation" in Ukraine.

"Putin might use the day to formally declare that Russia is at war with Ukraine"

Redrawing that plan is a great deal easier when you have control of the narrative your audience will see and hear, which of course President Putin largely does.

But even so, he will need to say something on Monday which rises to the importance of Victory Day and acknowledges the events which Russia put into motion on 24 February.

For many, that suggests that Mr Putin might use the day to formally declare that Russia is at war with Ukraine.

We have become used to referencing the Ukraine war since it began two and a half months ago, but in Russia it remains classed as a "special military operation".

Telling the Russian people it is now officially a war could do several things to help Mr Putin's war effort.

Russian soldiers march in Victory Day rehearsals yesterday

Firstly, it could bolster a sense of Russian pride to unify behind a common cause, making the hardships endured by war more understandable, if not more tolerable.

It would also have a very pragmatic effect, as it would allow Mr Putin to mobilise a war effort which could involve conscription.

Moscow has denied it plans to officially declare events in Ukraine a war on 9 May, describing the suggestion as nonsense, though it must be remembered that similar denials were issued about any plans for an invasion just days before Russian troops went into Ukraine.

At this point the need to deliver something, anything, that can be paraded as a victory could be influencing military decisions on the ground.

The ongoing standoff at the Azovstal steelworks in Mariupol is thought to be central to that story.

About 200 civilians, including children, are thought to be trapped in the tunnels and bunkers beneath Azovstal, along with Ukrainian soldiers making their last stand

Some Ukrainians believe the hope is that a major push this weekend would see Russia crush the last resistance in the plant in order to facilitate a Victory Day parade through the city of Mariupol.

The Kremlin has said it doesn’t know if there would be a parade in Mariupol on 9 May perhaps because there has been so much about this war so far which has not gone accroding to Moscow’s plan.

It’s hard to imagine what that parade would look like – through a city which has been demolished by two and half months of war, with residents trapped and traumatised by what they have lived through.

Buildings bombed to the point of not return. The city's dead lying in the streets or buried in makeshift graves on every street.

Vladimir Putin is a leader who is skilled at writing the narrative according to his own needs, but even he might struggle to sell those images as a rescue of the Ukrainian people.

A Kremlin spokesperson added "the time will come to mark Victory Day in Mariupol".

9 May and the pomp and ceremony in Moscow’s Red Square will be very different to what Moscow envisaged in late February, now that it’s clear President Putin cannot control the war he believed would be over within days.