GALLIPOLI, Turkey — For the first time at age 95, Bill Grayden has come to Gallipoli, where his father stormed the beach and took a bullet through his lung during the ill-fated British-led World War I invasion.

Grayden was among thousands of Australians and New Zealanders who made the pilgrimage from the southern hemisphere to this distant peninsula in Turkey. They joined world leaders at a dawn service Saturday marking exactly 100 years since the invasion, which had aimed to secure a naval route from the Mediterranean to Istanbul and take the Ottomans out of the war.

During the emotional ceremony, Britain’s Prince Charles and the prime ministers of Australia and New Zealand spoke of the heroism of the soldiers from their countries and other Allied nations.

“For so many, the rising sun that day would be their last,” Australia’s Chief of Defense, Air Chief Marshal Mark Binskin, told the crowd at Anzac Cove.

That was not the case for Bill Grayden’s father Len. Five days after the landing, the elder Grayden was found wounded and nearly motionless on the field. During the heat of battle, someone noticed a slight hand movement and he was evacuated to a hospital ship and ultimately survived. The subtle moment that determined his fate demonstrates how small differences can substantially change the course of history.

Len Grayden would return to Australia to raise a family. His son Bill later served in multiple campaigns in World War II and became a politician. He has raised 10 children of his own, and now has 44 grandchildren, 20 great grandchildren and so far one great-great grandchild.

The Gallipoli campaign marked the start of a fierce battle that lasted for eight months. Around 44,000 Allied troops and 86,000 Ottoman soldiers died.

The tragic fate of troops from Australia and New Zealand is said to have inspired an identity distinct from the British. The anniversary of the start of the land campaign on April 25, known as ANZAC Day, after the Australia and New Zealand Army Corps, is marked as a coming of age for both nations.

“In volunteering to serve, they became more than soldiers. They became the founding heroes of modern Australia,” Australian Prime Minister Tony Abbott said at the service.

The doomed offensive nearly ended the career of Winston Churchill, who as First Lord of the Admiralty came up with the plan he thought would help end the war.

A century later, officials from the countries representing both sides of the battles spoke of their respect for their former foes.

New Zealand’s Prime Minister John Key noted that when the ANZAC forces landed, Ottoman Turks were defending their homeland.

“We have coastlines similar to this at home. If the situation were reversed we know that New Zealand soldiers would have been willing to lay down their lives to defend their country,” he said.