Britain's King Charles and other senior royals joined veterans and crowds to watch a grand military parade and flypast at the start of four days of commemorations marking the 80th anniversary of Victory in Europe (VE) Day.
The UK government has planned a series of events in the run-up to the anniversary of Nazi Germany's unconditional surrender that took effect on 8 May 1945.
It is observed around that date in many countries, including France, the United States and Russia.
The celebrations, which come as US President Donald Trump is pressing for a deal to end the Russia-Ukraine war, kicked off earlier today when London's Big Ben clock struck at midday and extracts from British war leader Winston Churchill's VE Day speech were read out.
"My dear friends, this is your hour. This is not victory of a party or of any class," actor Timothy Spall said, reciting the words spoken by Churchill to cheering crowds eight decades ago.
"It's a victory of the Great British nation as a whole. We were the first, in this ancient island, to draw the sword against tyranny."
Alan Kennett, a 100-year-old Normandy veteran, began the procession which set off down Whitehall, through Admiralty Arch and up The Mall towards Buckingham Palace.
Thirty further veterans are to attend official events today, including 26 who will watch the procession in London.
The list includes Royal Navy veteran Albert Keir, 99; Royal Engineers veteran Alfred Littlefield, 101; RAF veteran Bernard Morgan, 101; Army veterans Arthur Oborne, 99, and Tom Stonehouse, 99; and Royal Marines veteran Francis James Grant, 99; who all served during D-Day.
More than 1,300 members of Britain's armed forces marched through central London, watched by the king, who offered a salute as they passed, alongside Queen Camilla, Prince William, his wife Kate and their three children, along with Prime Minister Keir Starmer, and veterans of the conflict.
Ukrainian armed forces also took part, carrying their nation's blue and yellow flag, in a gesture that underlined Britain's continued support for Ukraine in its war with Russia.
Addressing the British veterans in an open letter, Mr Starmer said: "I want you to know: the whole nation is inspired by the selfless dedication of your example."
"This week, the country will show you just how thankful we all are. Because we know, that without your service, the freedom, peace and joy that these celebrations embody, would not be possible," he said in the letter published by the government.
In 1945, VE Day was greeted by wild celebrations in London and across Britain.
The late Queen Elizabeth, then a 19-year-old princess, and her younger sister Margaret famously slipped out to join the throng outside Buckingham Palace, believed to be the only time during her 96 years she mingled with the public unrecognised.
The princess, who had served during the war as a volunteer driver and mechanic, was in uniform, her cap initially pulled down to her eyes because she was "terrified of being recognised".
Today's parade concluded with a flypast by historic military aircraft and the Royal Air Force's Red Arrows display team, watched by the royals from the balcony of Buckingham Palace, as crowds flocked below to take in the spectacle.
The royals, who waved to the onlookers gathered outside, were also due to host about 50 veterans and others who lived through the war for a tea party inside the palace.
"It's important to remember some of the poor devils who didn't make it like I did," 99-year-old Royal Air Force Veteran Dennis Bishop said.
Among other events, there will be a party on HMS Belfast - one of the few surviving British warships from WWII - which is moored on the banks of the Thames.
Watch: RAF veteran Dennis Bishop says he's 'absolutely overwhelmed' by the occasion
And people are invited to take part in hundreds of other parties, picnics, installations and commemorations that will take place across the country through the week until VE Day on Thursday.
Tomorrow, Queen Camilla will visit an art installation of around 30,000 ceramic red poppies - symbols of remembrance for the war dead - at the Tower of London.
Celebrations will draw to a close on Thursday with a two-minute national silence, observed by the royals and at government buildings at noon.
Pubs across the UK have been allowed to stay open two hours later as part of the celebrations.
"This 80th anniversary is a moment of national unity," Mr Starmer said in a statement.
"A time to celebrate that hard-won peace, honour the memory of those who lost their lives and remember the sacrifices made by so many to secure our freedom."
A new display of almost 30,000 ceramic poppies at the Tower of London formS another tribute.
The poppies have been set to resemble a wound to reflect the long-lasting sacrifices made during the war.
A service at Westminster Abbey will begin with a national two-minute silence of reflection and remembrance on Thursday, where veterans will be part of the congregation.
Horse Guards Parade will then hold a live concert to round off the commemorations.
Additional reporting PA
