On June 6, 1944, the Sydney man was a young Royal Australian Air Force pilot flying a Lancaster heavy bomber as D-Day, the world’s largest seaborne invasion, was launched by Allied forces to liberate Europe from Nazi rule.

Purdy was among the 3000 Australian soldiers, sailors and airmen taking part.

He had already notched up multiple bombing missions with the RAAF’s number 463 squadron, but he had no inkling when he took off from his base in eastern England about the historic events unfolding that day.

“We didn’t know until the night before that this was going to be the big attack to start the end of the war,” the 101-year-old told 9news.com.au.

Purdy’s aircraft was part of a force of about 150 Lancasters tasked with destroying a key German heavy gun battery at the Pointe du Hoc on Normandy’s coast.

Allied commanders believed its destruction ahead of a massive beach assault by a force of 130,000 troops was crucial to the success of D-Day.

He recalls the poor weather that made flying treacherous but also offered the advantage of surprise.

“We went across through bad weather, which we never would have flown into normally, but that was why we went out I guess,” he said.

“One of the reasons of the success was that the Germans thought that no one in their right mind would start an invasion when the weather was that bad.”

Then after his plane dropped its bombs and turned home, Purdy enjoyed a bird’s eye view of the English Channel packed with invasion ships as they approached the Normandy beaches.

“You could just see an endless row of boats as far as the eye could see,” he said.

“There were 5000 small boats bringing in the first 130,000 troops, and they were guarded by 300 ships of the line, including six battleships.

“And they were proceeded by 300 minesweepers to make sure everything was cleared.”

“When you saw the whole of the sea was just covered with boats, I always reckoned I could have put my wheels down and taxied back home after it.”

While the majority of Allied troops landing on D-Day were from the United States, Britain and Canada, forces from many other countries, such as Australia, were involved in the invasion.

They faced around 50,000 German troops.

A total of 4414 Allied troops were killed on D-Day. More than 5000 were wounded.

The exact German casualties aren’t known, but historians estimate between 4000 and 9000 men were killed, wounded or missing during the D-Day invasion.

Purdy completed 37 bombing missions between April and August 1944.

In March 1945, he was posted back to Australia in March 1945 to serve in the Pacific against the Japanese.

Following the surrender, he was transferred to the reserves.

During the 1950s he and a friend from the RAAF founded a frozen food distribution company.

Purdy went on to enjoy a successful business career before retiring.

Today he lives on Sydney’s North Shore.

– With Associated Press