Millions of scouts around the world have renewed their promises in ceremonies to celebrate the 100th anniversary of the movement's founding.
Scouts from more than 160 countries are camping at Brownsea
Brownsea Island, in Poole Harbour, Dorset, where the first camp for 20 boys was held by Robert Baden-Powell in 1907, is the focus of celebrations.
Some 300 scouts from 160 countries have set up camp at the National Trust site.
Some 40,000 scouts and leaders from across the world are also at a 12-day jamboree near Chelmsford, in Essex.
The Hylands Park event, opened on Saturday by Prince William, is believed to be the biggest event in the history of the Scout Association.
At Brownsea Island, 300 scouts assembled for a ceremony at 0800 BST (0700 GMT).
Chief Scout Peter Duncan, a former Blue Peter presenter, signalled the start of scouting's second century by blowing the original kudu horn that Lord Baden-Powell blew to start the first camp.
British scout Alastair Frankl, 16, read out Lord Baden-Powell's speech of 100 years ago.
He said: "Our aim is to bring up the next generation of useful citizens with a wider outlook than before and thereby to develop goodwill and peace in the world with comradeship and co-operation."
This would be "in place of the prevailing rivalry between classes, creeds and countries which have done so much in the past to produce wars and unrest".
The Dorset-based scouts led the world in renewing their scout promise to build a peaceful and tolerant society.
Some 400,000 scouts in the UK took part in hundreds of similar events.
Scouts around the globe also reaffirmed their scouting promise in ceremonies.
Events were held in places as far afield as Namibia and Ecuador while, in Bucharest, Romania, scouts formed a human chain around the parliament building.
There are now thought to be 28 million scouts worldwide.
Cardiff scout Jon Grimes, 19, said scouting was as relevant now as it was 100 years ago.
He said: "When [Lord Baden-Powell] first ran the camp, he brought together different social classes from public schools and less fortunate backgrounds. It was about crossing the social divide and making friends.
"Our camp this year will be about making friends between people from different cultures."
Mariama Irele, 17, from Senegal, said of the Dorset event: "Two days ago I arrived here on a boat with 300 strangers - now they are all my friends.
"If young people around the world can repeat what has happened here, then we really can help build a more friendly world."