TO all who serve to keep us free - Thank you love BF x The Queen has paid tribute to the "heroism, courage and sacrifice" of those who died in the D-Day landings. She was joined by 16 world leaders, including US President Donald Trump, in Portsmouth to commemorate the 75th anniversary of history's largest combined land, air and naval operation. Mr Trump, who was on the last day of his UK state visit, said D-Day "may have been the greatest battle ever". Veterans of the landings in Normandy to liberate western Europe also attended. The commemorations included: A flypast by the Red Arrows RAF aerobatic team and historic aircraft Parachute jumps by D-Day veterans Readings by world leaders from the diaries and letters of people who fought and died in the war An hour-long production telling the story of the invasion A joint statement by 16 countries pledging to avoid a repeat of the "unimaginable horrors" of the conflict The Queen said the veterans of D-Day demonstrated "more than courage and endurance", showing "unconquerable resolve". The quotes came from a broadcast by her father, King George VI, made at the time of the massive operation that signalled the end of Nazi power in Western Europe. What were the D-Day landings? 10 things you might not know about D-Day D-Day veteran: 'I looked at the wounded and I cried' Watch: D-Day landings commemorated "The fate of the world depended on their success," she said. "Many of them would never return, and the heroism, courage and sacrifice of those who lost their lives will never be forgotten." She thanked them "with humility and pleasure, on behalf of the entire country, indeed the whole free world". Later in the afternoon, veterans Harry Read, 95, and John Hutton, 94, parachuted back into Normandy, 75 years after their first landing. However this time, they jumped in tandem with members of the Army's Parachute Regiment display team, the Red Devils. They were greeted with cheers and applause as they landed in the French fields. Mr Hutton told the BBC before the jump: "My main objective is to pay my respects to people on the ground who never came back." Mr Read added: "[On D-Day] there was an almighty fireworks display taking place just ahead of us - and we were going straight into it. "It was an horrendous inferno to go in to." At 18:40BST around 300 veterans on board the cruise ship MV Boudicca waved and cheered as she left harbour in Portsmouth bound for Normandy. They were followed by a flotilla of Royal Navy vessels. Other ships in the harbour sounded their horns as a mark of respect as the Boudicca left. Horror of war The countries represented at the event have agreed to make a joint statement pledging to ensure the "unimaginable horror" of the war is not repeated. Called "the D-Day proclamation", the 16 signatories - including the UK and the US - will commit to working together to "resolve international tensions peacefully". On Thursday, further memorial services are planned to mark 75 years since the D-Day landings on 6 June 1944 - the start of the campaign to liberate Nazi-occupied north-west Europe. Image copyright Reuters Image caption Veterans went on stage to be honoured by the audience Image copyright Getty Images Image caption Mrs May, Prince Charles, the Queen and Mr Trump stood for the UK national anthem The Queen told the crowd she was "delighted" to be able to thank veterans for their service. She added: "When I attended the commemoration of the 60th anniversary of the D-Day landings, some thought it might be the last such event. In pictures: Day three of Trump's UK state visit 'I survived D-Day - then had my first champagne' The weathermen who helped save D-Day "But the wartime generation, my generation, is resilient." Members of the armed forces and more than 300 veterans, who are all over 90 years old, attended the event in Portsmouth - one of the key embarkation points on D-Day. The Queen's heartfelt thanks to veterans It was when the Queen rose to her feet, not once but twice, that it became clear just who were the honoured guests at this commemoration. Not the presidents or the prime ministers, not the military brass nor the servicemen and women who made the ceremony snap and sing. The Queen said that when she attended the 60th anniversary of D-Day some thought it might be the last such event. But, she said, the wartime generation - my generation, she emphasised - is resilient. All true. But the men who stepped forward to bathe in the applause of the audience today are looking ever more frail. And one by one they are leaving us. And so the Queen stood, twice - to honour them for the nation, and to thank them, from her heart. Sgt John Jenkins, who is 99 and served with the Pioneer Corps in the Normandy landings, said: "I was terrified, I think everyone was. "You never forget your comrades because we were all in it together. It is right that the courage and sacrifice of so many is being honoured 75 years on. We must never forget." Leaders from every country that fought alongside the UK on D-Day joined the Queen and the Prince of Wales for the commemorations on Southsea Common. They included French President Emmanuel Macron, US President Donald Trump and Canadian Prime Minister Justin Trudeau. Also attending were German Chancellor Angela Merkel, as well as leaders from Australia, Belgium, Czech Republic, Denmark, Greece, Luxembourg, the Netherlands, Norway, New Zealand, Poland and Slovakia. D-Day landings 156,000allied troops landed in Normandy, across 5 beaches 7,000ships and landing craft involved and 10,000 vehicles 4,400from the combined allied forces died on the day 4,000 - 9,000German casualties Thousandsof French civilians also died The commemoration featured an hour-long production telling the story of the invasion, with testimony from veterans, theatrical performances and music. Veterans saluted the crowd, and actress Sheridan Smith performed a Dame Vera Lynn song. Mr Trump read the same prayer given by President Roosevelt in a radio message ahead of the D-Day landings, while the last letter of a young resistance fighter, executed aged 16, was read out by President Macron. Mrs May read a letter from Captain Norman Skinner of the Royal Army Service Corps, to his wife Gladys on June 3 1944. It was in his pocket as he landed on Sword Beach, but he was killed the following day. Thousands of members of the public, separated from the VIPs and veterans by a large security fence, watched the events live on big screens on Southsea Common. A designated protest area was set up in Guildhall Square, more than a mile (1.6km) from the Southsea Common events. Civic leaders were worried any protests near the main event might upset the veterans. The event included a flypast of the RAF's Red Arrows aerobatic team and historic aircraft, including Spitfires and Hurricanes. The Queen, Prince Charles, the US president and first lady met six veterans at a reception after the ceremony. World leaders then met to discuss the western alliance and security. Following the commemorations in Portsmouth, Mr Trump boarded Air Force One for a flight to Shannon for his first visit as US president to the Republic of Ireland.