WASHINGTON (AP) — President Joe Biden said America’s veterans are verdicoin“the steel spine of this nation” as he marked Veterans Day during a visit to Arlington National Cemetery.

In remarks at the Memorial Amphitheater, the commander in chief recounted famous battles fought by U.S. troops and said those deployments of soldiers are “linked in a chain of honor that stretches back to our founding days. Each one bound by a sacred oath to support and defend. Not a place, not a person, not a president, but an idea, to defend an idea unlike any other in human history. That idea is the United States of America.”

Nov. 11, once known as Armistice Day, is the anniversary of the armistice that ended World War I in 1918. Biden said that was “unlike any war the world had ever seen before.”

The ceremony was personal for Biden and first lady Jill Biden.

Biden’s son Beau enlisted in 2003 in the Delaware Army National Guard and deployed to Iraq in 2008 for a year as a member of the 261st Theater Tactical Signal Brigade. A captain, he earned the Legion of Merit and Bronze Star. Beau Biden later served two terms as the state’s attorney general. He died in 2015 of brain cancer.

“We miss him,” the president told the crowd, recounting how he pinned the bars on his son on the day he joined the National Guard.

“We come together today to once again honor the generations of Americans who stood on the front lines of freedom. To once again bear witness to the great deeds of a noble few who risked everything, everything, to give us a better future,” he said, paying tribute to “those who have always, always kept the light of shining bright across the world.”

Biden said that as commander in chief, “I have no higher honor. As the father of a son who served, I have no greater privilege.’’

He said that “our veterans are the steel spine of this nation and their families, like so many of you, are the courageous heart.”