D-Day was scheduled for the morning of June 5, 1944, but a storm was brewing and a British meteorologist convinced General Eisenhower to press pause. The weather would have been totally unsuitable for tens of thousands of troops to successfully storm the coast of Normandy, or drop from the air, while under massive German fire.

The next night, despite a significant swell, the largest armada in history left ports along the southern coast of England towards beaches whose code names are now well known: Sword, Juno, Gold, Utah and perhaps most famous of all, Omaha.

It was an operation as epic in scale as it was in aspiration. There were 7000 ships and landing craft carrying some 150,000 troops. The allied navies were there to ferry soldiers, tanks, trucks, artillery, food and equipment, and to bombard German defences.

Some observers said the flotilla heading to Normandy was so large that there appeared to be “more ships than sea”. There was a similar effect in the skies above, with 11,600 aircraft taking part in the invasion. Churchill called it “the most difficult and complicated operation ever undertaken”.

There were other unseen participants whose crucial role was not revealed for decades. The Allies would not have prevailed in Normandy without the intelligence streaming in from Bletchley Park where 9000 women and men toiled undisclosed in three shifts every day, year after year, breaking the Nazi codes and analysing the critical intelligence that helped significantly shorten the war, saving countless lives.

It was an extraordinary time of interconnected events when history itself seemed to be racing. There could have been no D-Day unless the RAF, whose fighter pilots, alongside those from Australia, New Zealand, Poland, Czechoslovakia and Canada, had not won the Battle of Britain. There could have been no D-Day without the Eighth Army’s victory at El Alamein in the North African desert – the “end of the beginning”.

Unlike so many wars before and since, these Normandy veterans fought to liberate not to conquer, to free the innocent not to crush them.

In June 1944, “Victory in Europe” was still almost a year away but there could have been no VE Day without the massive sacrifice of Soviet troops and citizens on the Eastern Front. The turning point was the Battle of Stalingrad, with its millions of casualties and a decisive victory over German forces.

On the Western Front, there could have been no VE Day without D-Day.

On the night before June 6, back in ports such as Portsmouth, the one-day postponement added to the extraordinary tension of those waiting with their equipment to board ships, landing crafts, planes and gliders. The atmosphere was electric with a potent mix of fear, excitement and when they finally set sail, seasickness and the smell of vomit.

These young soldiers, from so many countries, were by now well-trained and ready but they had big questions on their minds. Would they be up to the task? Who would and wouldn’t survive? Would they see their sweethearts again? Would they ever return home?

At the 70th anniversary, President Barack Obama summed up the atmosphere the night before the Longest Day: “If prayer were made of sound, the skies over England that night would have deafened the world.”

The mission’s purpose could not have been clearer. Europe was enslaved by the greatest tyranny. Once proud nations were in chains. Millions were dying in concentration camps such as Auschwitz, Dachau and Bergen Belsen. Civilisation, itself, was in peril.

The task of these young citizen-soldiers wasn’t simply to storm the Normandy beaches and punch through Hitler’s massive “Atlantic Wall”. Their job wasn’t only to secure and then defend a foothold in France and expand from there. Their mission was to free half a continent.

There had already been some practice with amphibious landings in Sicily, Salerno and Anzio the year before, but none of these coastlines had been as fortified as Normandy with its miles of the thickest steel reinforced concrete plus colossal gun emplacements, batteries, tank traps, artillery, minefields and thousands of miles of barbed wire.

At Omaha, soon to be known as “Hell’s Beach”, machine gun and mortar fire cut to pieces so many young men wading ashore. It was the toughest start but one month later there were nearly one million Allied soldiers in Normandy. The rescue of Western Europe was on its way.

US soldiers attend a wreath laying ceremony at the 1st Infantry Division Monument as part of ceremonies marking the 80th anniversary of D-Day, near Omaha Beach, Normandy, this week. Photo: AP/Jeremias Gonzalez

In Adelaide 20 years ago I had lunch with Normandy veterans. Some had been on Sword and Gold beaches that first morning, fulfilling Churchill’s promise to “fight them on the beaches”, except it was on the other side of the English Channel. Others had parachuted in during the night, dropping behind enemy lines onto French farmlands.

They had all seen the most terrible things: a blood-soaked shoreline, friends cut down beside them, young lives cut short. At our lunch, I was struck by their spontaneous decency, good-hearted humour, and teasing of mates, particularly those who had arrived “late” on day two or three.

None glorified war. None saw themselves as heroes. They simply had a job to do. A job that had to be finished. A war that had to be won.

Unlike so many wars before and since, these Normandy veterans fought to liberate not to conquer, to free the innocent not to crush them. Their prevailing motive was not racism or some kind of cruel revenge, born of ancient hatreds, but a shared sense of duty.

The veterans I met in Adelaide were prepared to give everything, including their lives, for the next generation of their own kind but also for the freedom of peoples they didn’t know. They had one other objective after they “had done their bit”. It was not to plunder or subjugate but to return home to “Civvy Street” and to get on with the rest of their lives, including migrating to Australia.

Let’s also remember in these troubled times that the Normandy veterans were part of a generation who didn’t leave smashed cities and broken peoples behind but had leaders who quickly supported the rebuilding of nations the Allies had just fought.

Today there will be very few D-Day veterans left to join President Biden, King Charles, Emmanuel Macron and other world leaders at the 80th anniversary ceremonies in Normandy. Most will be in wheelchairs tended by loving children and grandchildren. Those who can will stand a little taller today as they salute and remember their comrades. As they do we should honour and thank them for changing the trajectory of our lives, for the better.

We should also ask ourselves in these current times of conflict and peril, including the immense global threat posed by climate change, whether we are up to the challenges ahead, as they were 80 years ago.

Mike Rann, a former Premier of South Australia, was the Australian High Commissioner to the UK from 2012 to 2014. At the time he was also Australia’s Commonwealth War Graves Commissioner and a Trustee of the Imperial War Museum.