Russia's withdrawal from Kherson marks "another strategic failure", the Defence Secretary has said.
It is anticipated that Ukraine has now retaken large areas of the Kherson region on the western bank of the Dnipro River, with its forces largely in control of the city itself.
Ben Wallace said: "In February, Russia failed to take any of its major objectives except Kherson.
"Now with that also being surrendered, ordinary people of Russia must surely ask themselves "What was it all for?"
Russia said its troops finished withdrawing from the western bank at 5am local time on 11 November, paving the way for Ukrainians to cautiously move towards reclaiming the territory.
Videos and pictures posted on social media later showed residents celebrating in the streets, with the Ukrainian flag flying over a central Kherson square.
Ukraine is yet to claim the city is back in Ukrainian hands, but the country’s president Volodymyr Zelensky said "life is returning".
It is anticipated that Ukraine has now retaken large areas of the Kherson region on the western bank of the Dnipro River, with its forces largely in control of city itself.
The retreat, which was ordered amid a Ukrainian counter-offensive, represents a huge blow to president Russian president Vladimir Putin – who has so far remained silent on the development.
Watch: Ukraine releases footage of artillery barrage towards Russian positions.
Kherson was one of the first Ukrainian cities to be captured in the war Moscow waged on its neighbour from 24 February.
Russian forces still control about 70% of the wider Kherson region in the wake of the withdrawal.
In an intelligence update posted on social media, the UK Ministry of Defence said Moscow's troops had "highly likely" destroyed road and rail bridges over the Dnipro River as part of their retreat.
The exit was formally announced on 9 November, but the defence experts said it is likely it started as early as October 22, when Russian-installed figures urged civilians to leave.