De Haviland Mosquito FB.VIs of 248 Squadron attacking a German 'M' Class minesweeper and two trawler-type auxiliaries in France 1944 (Picture: MOD).
It is 80 years to the day since Britain declared war on Adolf Hitler's Nazi Germany.
At 11:15am on 3 September 1939, Prime Minister Neville Chamberlain admitted to the nation in a sombre radio broadcast that his "long struggle to win peace" had failed.
Hours later, France issued its own ultimatum to Germany, setting in train the Second World War.
It was a conflict which lasted nearly six years and cost around 50 million lives.
Mr Chamberlain's announcement came two days after Hitler's forces invaded Poland.
The radio address was made from the Cabinet room in 10 Downing Street.
He said: "This morning the British ambassador in Berlin handed the German Government a final note stating that, unless we heard from them by 11 o'clock that they were prepared at once to withdraw their troops from Poland, a state of war would exist between us.
"I have to tell you now that no such undertaking has been received, and that consequently, this country is at war with Germany."
Mr Chamberlain continued his broadcast by saying it was "a bitter blow" that his "long struggle to win peace" had "failed".
"Yet I cannot believe that there is anything more or anything different that I could have done, and that would have been more successful," he added.
He concluded his broadcast: "Now may God bless you all and may he defend the right.
"For it is evil things that we shall be fighting against - brute force, bad faith, injustice, oppression, and persecution. And against them, I am certain that the right will prevail."
A year earlier, Mr Chamberlain returned to London from talks in Munich clutching an agreement signed by Hitler that he said meant "peace for our time".
But the German leader continued his aggression in Europe, culminating in the invasion of Poland.
Ray Smith, from Northampton, said he was around 15 when Mr Chamberlain made the declaration.
The 94-year-old said the gravitas of it all did not sink in, adding: "I don't suppose at that age you realise quite what it was."
Joining the Royal Navy at 17, a year later he took part in D-Day, serving onboard HMS Middleton, the ship which supported troops landing on Sword beach.
With no time to be worried or scared, he said that even though it was the summer it was "really rough weather", with equipment and tanks initially being dropped too far out.
"When the ramps went down and they [the troops] jumped in, they just vanished with all of the gear on," he said.
Describing the waters of Normandy, Mr Smith said there were "bodies floating everywhere".
There have been no official major UK events planned to commemorate the 80th anniversary of Britain's declaration of war, after which the country went on to suffer an estimated 400,000 military and civilian casualties.
However, Foreign Secretary Dominic Raab joined more than 40 world leaders in Warsaw at the weekend for a ceremony marking the outbreak of the conflict.
On Sunday, Prime Minister Boris Johnson praised the "dogged and unconquerable resistance" Poland displayed during the Second World War, 80 years after it was invaded by the Nazis.
The Polish people "never succumbed to tyranny", Mr Johnson said.
He added: "Today Poland lives and thrives in the heart of Europe, just as Churchill foretold."
The UK has stood with Poland "in times of triumph and tragedy."
Meanwhile, Defence Secretary Ben Wallace said Britain went to war to "defend our values and our allies from the Nazis".
He added: "Even though nearly every family in the UK still possessed the memories and hurt of the First World War, they were prepared again to make the ultimate sacrifice.
"The incredible courage of that generation who fought for our freedom must never be forgotten."