One hundred years ago, on April 6, 1917, the United States entered World War I.

To mark the occasion, several thousand people will attend a national commemoration in Kansas City, home to the National World War I Museum and Memorial.

In St. Louis, an exhibit opens today at the Missouri History Museum. It focuses on the role St. Louisans played — on the battlefield and the home front.

And, renovation work continues downtown at the Soldiers Memorial, which opened in 1938 to honor the 1,075 St. Louisans who died in the war.

Mary Delach Leonard | St. Louis Public Radio

Here are some things to know about the war centennial:

1. Some history: Why they called it “The Great War”

World War I was known as The Great War because it was bigger and bloodier than any war the world had seen. More than 8 million soldiers and an estimated 13 million civilians died in the four-year war.

The war started in Bosnia in 1914, with the assassination of Archduke Franz Ferdinand of Austria-Hungary, and eventually spread throughout Europe. The United States entered as an Allied nation, on the side of France, Great Britain, Russia and Italy. Germany led the Central Powers that included Austria-Hungary, Turkey and Bulgaria.

The fighting had ravaged Europe for three years by the time President Woodrow Wilson appealed to Congress and his fellow Americans to help defeat the German Empire — to make the world safe for democracy.

After the sinking of American ships by German U-boats, Wilson said the United States could no longer stay on the sidelines. Congress declared war on Germany on April 6, 1917. More than 50,000 American soldiers died in combat during the war; another 50,000 died of disease and other causes.

Some had believed — or hoped — that World War I would be “the war to end all wars.”

Although the Great War was overshadowed by World War II, it led to the world we live in today, said Patrick Allie, military and arms curator of the Missouri Historical Society. The United States established itself as a world power. And the divvying up of the German and Ottoman empires after the war changed the makeup of Europe and the Middle East and set the stage for today’s conflicts.

Missouri History Museum

2. St. Louis stepped up

More than 156,000 Missourians served in World War I, according to the Missouri State Archives. Nearly 10 percent of Missouri’s 11,000 casualties were from St. Louis.

Many soldiers from St. Louis served with the 35th and 89th Army divisions in France and Belgium and were in the thick of the fighting along the Western Front, said Allie, who's the curator of the “World War I: Missouri and the Great War” exhibit at the Missouri History Museum.

“They were largely involved in the Meuse-Argonne offensive, which was the final American offensive of the war that brought the war to the end,’’ Allie said. “And a number of St. Louisans received the Medal of Honor for actions. They were right there in the front lines fighting, which is why I think you see that number of casualties for St. Louis.’’

Missouri History Museum

As patriotism swept across the nation, St. Louisans worked in weapons plants, joined the Red Cross and bought U.S. war bonds. But the city’s large German population faced a different wave: hostility.

“You see a lot of changes,’’ Allie said. “German being taken out of high schools as a language that could be taught. Streets like Von Versen or Berlin being changed to Pershing and Enright, who was the first American killed overseas during the war. You had a lynching over in Collinsville of a German immigrant. It really came home for people.’’

The war came at a formative time in St. Louis, when workers were fighting for better wages and working conditions, Allie noted.

“Most of the workers in the lead mines and in industries across the city were immigrants or were second-generation Germans, and you had them striking — trying to get workers' rights. And that gets tied into the war and how they’re perceived,” he said.

Mary Delach Leonard | St. Louis Public Radio

3. Renovations continue at the Soldiers Memorial

The city’s lasting monument to the war — the Soldiers Memorial on Chestnut Street — will miss the April 6 anniversary, but will reopen in time for Veterans Day 2018, the centennial of the armistice that ended World War I.

The memorial is one year into a $30 million renovation project that will update the structure and double its museum space. The Missouri Historical Society, which took over the memorial’s operation in 2015, is overseeing the project.

During a recent tour of the site, Karen Goering, project coordinator, stressed the importance of preserving the Art Deco building.

“We’re working to be very respectful of the original architecture. There’s a lot of marble and stonework, granitoid floors, and we have kept the original display cases that are beautiful and original to the building,’’ she said. “The cenotaph in the loggia is black granite and includes the names of 1,075 individuals from the St. Louis area who made the ultimate sacrifice. It’s absolutely beautiful. There’s just these architectural gems throughout the building.’’

Mary Delach Leonard | St. Louis Public Radio

A major part of the project involves adding a heating and cooling system, which the building had lacked. That will be good for visitors, as well as for protecting the museum’s artifacts, Goering said.

Workers are cleaning the exterior of the structure and removing layers of coal dust from the sculptures outside the building. Several hundred tiles that are missing from the Gold Star Mothers mosaic in the ceiling of the loggia are being replaced. A ramp is being added at the 13th and Chestnut streets entrance to make it more accessible.

The project includes the narrowing of Chestnut Street in front of the Memorial to connect it with the Court of Honor, which honors St. Louisans killed in World War II. The court also is being redone to add a reflecting pool and fountain.

Financing for the Soldiers Memorial was part of a 1923 bond issue that transformed much of downtown St. Louis, Goering said. Voters approved $6 million to clear seven blocks for the memorial plaza and to build the structure.

“It was densely populated. There were a number of businesses, and there were residences. Right on the corner of 13th and Market was a lumberyard,’’ she said. “It took longer than they expected to clear the property, and they didn’t have the funds left to build the memorial.’’

The memorial would eventually be built as a work project of the Great Depression.

“When the Public Works Administration came along in the 1930s, St. Louis had this shovel-ready project, and so this became part of that project,’’ Goering said. “In 1936, Franklin Roosevelt came to St. Louis and dedicated the site. The Soldiers Memorial opened to the public on Memorial Day 1938.’’

The renovation is being funded by anonymous donors, not tax money, Goering said.

Curators also are cataloging thousands of artifacts donated through the years by St. Louis veterans and their families. Allie says some of the items were stored in the basement of the memorial and forgotten.

“I opened a box, and there were about a half-dozen German Pickelhaubes, which were the German helmets with the spikes on top,’’ he said. “These were brought back as souvenirs by soldiers. It was part of their wartime experience.’’

To learn more:

* Read about the American involvement in World War I on the website of the National World War I Museum in Kansas City.

* Visit the website “Over There: Missouri & the Great War,” a statewide, digitization project that includes historical documents and photographs from museums, archives, libraries, and private collections from across Missouri.

Follow Mary Delach Leonard on Twitter: @marydleonard