It’s July 4, the day on which we Americans traditionally celebrate our freedom from tyranny and oppression.

For me, there’s no better way to appreciate those freedoms than to look back and consider the sacrifices of generations past.

Today I happened upon a remarkable story about a man who saved 669 lives—but who didn’t speak a word about it for almost 70 years. He recently met the beneficiaries of his actions.

Nicholas Winton was 29 when a friend invited him to visit Czechoslovakia in December of 1938. Winton was packing for a skiing holiday in Switzerland when his would-be holiday companion told him to come urgently to Czechoslovakia instead. Adolf Hitler’s forces had occupied the country’s Sudetenland, and his friend wanted him to see it first-hand.

Winton was appalled to see the refugees’ living conditions. In other parts of central Europe, “kindertransporten” were already evacuating children to concentration camps. But Czechoslovakia didn’t yet have an organized program.

Winton immediately started raising money and organizing trains to save the children. When he returned to Britain he devoted himself to finding homes and obtaining visas for the children, while still holding down his day job in London.

Word of Winton’s audacious plan quickly spread throughout Prague. When he returned to the Czech capital and set up office in his hotel room on Wenceslas Square, long lines soon formed outside. Parents pleaded with him to take their children.

“They knew all too well what their fate was likely to be. Their first thought was for the little ones. Never themselves. Practically all those parents perished in the camps,” Winton recalled in a 1997 interview. “Those parents were desperate—it was heartbreaking to listen to their stories.”

All told, Nicholas Winton saved 669 children from the Nazis. And last year, those “children”—now in their 60s—showed up at a ceremony in his honor.

“What will I say when I see Nicholas?” said Eve Leadbeaterives in Nottingham. “I will say ‘thank you’. What else is there to say?”

When we look back at some of the most momentous turning points in history, we usually find a single courageous individual.

It seems fitting today to think of the people who gave—and who continue to give—their lives for truth, justice, and the ideals we hold most dear. It also seems fitting to say “thank you.” What else is there to say?

Happy Independence Day.