VOLGOGRAD: The city of Volgograd was renamed Stalingrad for a day Saturday as Russia marked the 70-year anniversary of a brutal battle in which the Red Army defeated Nazi forces and changed the course of World War II.

Commuter buses emblazoned with pictures of the feared Soviet dictator ran across the southern city as patriotic Russians remembered what many view as the Soviet people's greatest achievement.

The half-year battle in 1943 in the city on the Volga River -- much of it fought in hand-to-hand combat across the ruined streets -- claimed the lives of two million people on both sides and eventually led to the German troops' surrender.

The battle marked Hitler's first big defeat and led to a Nazi retreat from Soviet territory after a lightning June 1941 invasion that had caught Stalin completely unaware.

The pulverised city was renamed Volgograd in 1961 after Soviet leaders admitted the extent of Stalin's tyranny during his decades in power.

But the old city name has remained synonymous with the battle and Volgograd lawmakers have decided to revive it for the anniversary and five other days of the year.

"We will defend our country by commemorating the great Battle of Stalingrad -- our great victory," Deputy Prime Minister Dmitry Rogozin told veterans who gathered on the city's central square at the start of the commemorations ceremony.

"Any enemy and potential aggressor should see this, understand this and feel this," the close ally of President Vladimir Putin said.

Putin -- due to attend a fireworks display and concert in Volgograd later Saturday -- has never denied Stalin's murderous purges of innocent citizens and deadly forced collectivisation.

But he and other modern leaders have preferred to overlook the disastrous errors in military strategy Stalin made during the war.

And Putin in particular has preached a patriotic message since returning to a third term in the Kremlin last year.

Analysts believe this has helped him maintain support among many of the older middle class voters in the face of the first street protests of his rule among the young.

State media focused their attention on Volgograd throughout the week as they detailed the lavish preparations and Kremlin's attention to veterans.

The start of the Volgograd commemorations were broadcast live on the national news channels while state television was due to broadcast a new dramatised documentary that promised to reveal new secrets about a "battle which changed world history".