(Reuters) - Americans mark the 100th anniversary of the armistice that ended World War One on Sunday with celebrations ranging from high-tech light shows to somber gatherings in honor of the country’s military veterans.

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More than 100,000 Americans died in World War One, after the United States declared war on Germany on April 6, 1917, driving the nation into a global conflict. Although the United States entered the war in the later stage, many Americans had disagreed with the decision to join allies Britain, France and Russia, some viewing it as an endless fight between old European rivals.

The conflict erupted in 1914 after a teenage Bosnian Serb assassinated Archduke Franz Ferdinand, the heir to the Austro-Hungarian throne, and his wife in Sarajevo. That lit the fuse for a war that would rewrite the world order, spell an end to empires, and claim the lives of more than nine million soldiers.

Lessons learned from World War One are more relevant than ever today, said Dr. Matthew Naylor, President and CEO of the National WWI Museum and Memorial in Kansas City, Missouri.

“In a world of increased globalization, radicalization and national tensions, it’s clear that the lessons of the Great War endure to this day,” Naylor said in a statement.

“The world today is more like the world of 1914 than it has been for the past 104 years. As we mark the 100 years since the Armistice, it is essential that we not sleepwalk into catastrophe,” said Naylor, who did not elaborate.

World War One, also known as the Great War, ended when world leaders at the 11th hour on the 11th day of the 11th month signed an armistice ending four years of bloody battles. Americans honor their war heroes, both living and dead, each year on Nov. 11 with ceremonies to mark Veterans Day, a national holiday.

The 100th anniversary of the peace agreement lends an extraordinary look to this year’s commemorative ceremonies around the United States, where wreaths are placed on memorials and bells toll to ring in harmony.

In Washington, the National Cathedral was due to hold an interfaith worship service to remember the 4.7 million Americans who served in World War One and honor the U.S. military’s work preserving peace and liberty since then.

During the service at 11 a.m EST (1600 GMT) the Cathedral will lead a national tolling of bells called the Bells of Peace, in what organizers called the spirit of tradition, honor and remembrance.

One of the most striking events is at the museum in Kansas City where a massive light installation appears to cover a memorial in 5,000 poppies. The flowers signify remembrance after Canadian physician Lieutenant-Colonel John McCrae saw them growing in a battle-scorched field in Waregem, Belgium and was inspired to write the poem “In Flanders Fields.”

The illumination covering the memorial in poppies ran for nine consecutive evenings through Veterans Day to recognize the nine million soldiers worldwide who died during World War One.

(Changing “marked” to “mark” in first paragraph.)