On today’s date, 75 years ago, the Allied forces launched the largest offensive by sea in history, the invasion of Normandy, France, to establish a beachhead in continental Europe. More than 5,000 ships and 13,000 aircraft carried more than 160,000 allied soldiers into battle that day, including an estimated 73,000 Americans.

Known as D-Day, it is one of those dates marked in history, taught in schools and long-remembered, like Dec. 7, 1941, July 4, 1776 or Sept. 11, 2001. Time can even brand historic events significant by year alone, such as 1492 or 1929.

Dates are the nails upon which history is hung, providing detail and context necessary to cement the lessons to be learned. Often, however, what we eventually take away from such dates is big-picture significance — that in 1492 Columbus set sail for Japan and instead arrived in the Bahamas, thus “discovering America,” or that the stock market crashed in 1929, triggering the Great Depression.

Lost is the human element, the effect on those involved in the events.

For example, the battle for the beaches of France — 50 miles of them — that began on June 6, 1944, lasted for weeks before the allies broke through and headed for Paris. During those weeks of battle, more than 30,000 American troops died, and tens of thousands more were injured. Many remain listed as merely “missing.”

That’s thousands of families that lost a father, son or brother, or saw them return wounded. It means thousands who lived the rest of their lives blind, deaf or as amputees. And among those who survived physically intact are thousands living with having killed or having seen their friends die.

The aphorism “those who fail to remember history are doomed to repeat it” is usually applied strategically — that is, concerning the broad view of results, such as whether to attack or talk, expand or retrench. But there’s another reason to remember history: It keeps us sane; it reminds us the cost of war is not only in land or money but also in the lives of those who serve and fight.

It’s worth remembering June 6, 1944, as not only a day in which a key battle began, but also as a day on which a lot of brave people faced certain danger, and forged ahead to keep those back home secure and free.

Through the years, we have told the stories of a number of local veterans of World War II. This has helped keep the dates marking key moments in that war relevant. Those stories are harder to find these days. There are fewer than a half-million World War II veterans remaining in the U.S., and the Department of Veterans Affairs says an average of 348 die each day.

Those remaining D-Day participants who were 20 years old at the time are now 95. In 10 years, there will be only a handful left. Then there will be none.

The idea that the sacrifice of so many can become so much historical trivia is both reassuring and unsettling.

It’s reassuring that as a nation, we enjoy the degree of security we’ve attained during the past 75 years, where military service is a choice and the loss of even a few of our soldiers captures national attention. Yet we’re reminded today of a time when thousands perished in a matter of hours or days to protect our future.