On social media there was a blizzard of videos. There were the people in BalakliyaA city of 27,000 people in eastern Ukraine. hugging Ukrainian soldiers. There were the piles of ammunition abandoned by the Russians. There was a tank fleeing so fast it crashed into a tree.

And there were the soldiers who tore down a Russian poster and found a poem by Taras ShevchenkoA Ukrainian poet and folklorist who died in 1861.. "Battle on - and win your battle!" it read.

Their success has amazed even Ukrainians. Since Wednesday, they have recaptured an area more than twice the size of Greater London - around 1,100 square miles.¹ In 24 hours, they drove the enemy out of over 20 towns and villages.

Most importantly, they forced the Russians to retreat from the cities of Izyum and Kupiansk. Both are vital railway hubs.

In some places, the Russians just dropped their rifles and fled on stolen bicycles.

One expert at West PointA name for the United States Military Academy. has called it "the greatest counter-offensive since World War Two." A Russian expert² compared it to the Battle of Mukden - a defeat by Japan in 1905 which led to riots in Russia.

The Ukrainians had a brilliant plan. For weeks they talked openly about freeing the southern city of Kherson.

So the Russians started moving troops south, leaving Kharkiv in the northeast poorly defended. They did not believe that Ukraine could attack them in both places.

They could not have been more wrong. Ukraine did attack Kherson - but the main attack was on Kharkiv. The Russians there quickly fled.   

The timing was vital. The Ukrainians needed to show before winter that victory was possible. If they did not, people in Europe relying on Russian gas would pressure them into making peace. Now Western countries will be encouraged to keep on supplying weapons.  

 "The war is not over," says Mick Ryan, an Australian general. "But perhaps the tide is finally turning."

Yes: Ukraine's success has been a devastating blow to the Russian army's morale. It is now torn between two fronts, one in the north and one in the south of Ukraine, and it is struggling to defend both.

No: Russia can still inflict a huge amount of damage, as it has shown by rocket attacks on Kharkiv's water and power supplies. Worse still, it could resort to using tactical nuclear weapons.

Or... This war is already a defeat for all of us - a reckless waste not only of human life, but of money and technical resources that could have been focused on the overriding problem of climate change.

Balakliya - A city of 27,000 people in eastern Ukraine.

Taras Shevchenko - A Ukrainian poet and folklorist who died in 1861.

West Point - A name for the United States Military Academy.