The Queen is being joined by Prime Minister Theresa May and US president Donald Trump alongside 300 veterans in Portsmouth for a ceremony ahead of Thursday's anniversary of 75 years since the D-Day landings.
Some 60,000 members of the public are expected to attend the Portsmouth Naval Memorial on Southsea Common for the event which pays tribute to those who took part in the biggest amphibious invasion in military history in 1944.
The world leaders are gathering for a photo at 10.45am before the ceremony begins at 11am. Later the Queen and Mr Trump will meet veterans and the US president will later join US service personnel.
It is the last event on Mr Trump's UK leg of his tour before he flies to Ireland this afternoon.
There will also be events in Normandy, including a parachute display at Ranville, and a vigil at Pegasus Bridge.
The Queen has arrived for the D-Day commemorations in Portsmouth marking the 75th anniversary of the Second World War campaign, but is not due to take her seat in the royal box for some time.
Earlier, Labour leader Jeremy Corbyn has paid tribute to the "unimaginable heroism" of the troops who took part in the D-Day landings.