The singer and actress, who sang the iconic There'll Be Blue Birds Over The White Cliffs of Dover, was known as the Forces' Sweetheart, having entertained troops during the Second World War. Calling on people to stay resilient through the crisis, she said: "We should take comfort that while we may have more still to endure, better days will return". There was no one else raising funds to help at that time, so it was groundbreaking work.
Dame Vera's family confirmed she died on Thursday morning surrounded by her close relatives.
She had also adopted a new stage name, Vera Lynn, borrowing her grandmother's maiden name.
Prime Minister Boris Johnson said her "charm and magical voice entranced and uplifted our country in some of our darkest hours".
"The voice like a bell was a gift, which she shared so generously and bravely".
Her Majesty sent a private message of condolence to Dame Vera's family according to Buckingham Palace.
Born in London's East End in 1917, Lynn became a household name during the war years.
She was given her own radio programme and, thanks to the BBC's shortwave transmitters, could be heard across the world.
A performer from the age of seven, Lynn also starred in films, enjoyed a number of post-war hits and was made a Dame of the British Empire in 1976.
The Guardian writes, "From the age of 18 she began performing with orchestras in the United Kingdom and released her debut solo recording, Up the Wooden Hill to Bedfordshire, in 1936, while she worked in an East End shipping company".
She was also the oldest artist to earn a top 40 album in the United Kingdom after her greatest hits album reached number 30 amid the 75th VE Day anniversary in May. "I am very sorry to learn that she has gone, but thankful for the 103 years she gave us". She developed emphysema in the latter part of the 1960s and performed less frequently.
They remembered her many appearances, and the fact that she travelled to Burma to entertain the troops, one of the few entertainers to take on the hard journey.
Lynn Wednesday Lewis, a clarinetist and saxophonist, in 1941 before the couple went on to have one child, daughter Virginia, in 1946. Lynn's husband passed away in 1998.
Dame Vera was recognised for her services to entertainment and charity in 2016 after being made a Member of the Order of Companions of Honour in the Queen's Birthday Honours.
Pilar Cloud, executive manager of the Dame Vera Lynn Children's Charity, said: "We have been extremely honoured to have had Dame Vera Lynn as our president and she was always a very passionate and wonderful ambassador for this charity".
This breaking news story is being updated and more details will be published shortly.