Military pathologists believe that a British outpost in Étaples, France was the epicenter of the outbreak. In the winter of 1916-17, with World War I still raging in Europe, reports of a new disease — one with a rapid onset and high spreadability — circled through the camp. When soldiers returned from the battlefields, they brought that disease with them.

Eventually, hospitals were so overcrowded that overflow facilities, like this one at the Eberts Field military base in Arkansas, were created.

The MLB delayed its 2020 season due to COVID-19. But during the 1918 flu pandemic, baseball players, umpires and fans donned masks and headed to the diamond.

During the 1918 pandemic, the New York Health Board's stance regarding wearing masks was: "Better be ridiculous than dead."

In nations involved in World War I, government censors prevented local newspapers from reporting on outbreaks.

Spain remained neutral, though, and their press reported freely.

That censorship — in countries like Britain, France, Germany and the United States — led to the misconception that Spain was the origin of the virus. The Spanish flu name stuck.

In St. Louis, Missouri, shortly after the first cases of flu were detected, local health officials ordered schools, churches, courtrooms and libraries closed. Gatherings of more than 20 people were banned. This limited the number flu deaths in the city.

But not every city was as vigilant. There's not a mask in sight in this photo of a 1918 Memorial Day parade in Philadelphia. The death toll ended up being much higher there than in cities with stricter lockdowns.

The 1918 flu killed 675,000 Americans. "That's equivalent to 225 to 450 million people today," said John Barry, a scholar at Tulane University and author of "The Great Influenza."  "The numbers are staggering." 

Many of the headlines on the front page of the Seattle Daily Times from October 5, 1918, look a lot like the headlines from spring 2020.

Some people believed that a bag of camphor around the neck could prevent the rapidly spreading flu.

In February 1919, a woman wore this flu mask connected to two machines with a long hose.

A Seattle streetcar conductor turned one commuter away because he wasn't wearing a face mask.

In addition to masks, many believed that gargling with warm salt water and mouthwash would stave off infection.

In San Francisco, court was held in a park in an attempt to curb the spread of the deadly flu.

In San Francisco, the congregation of the Cathedral of Saint Mary of the Assumption gathered to hear Mass.

Windows were kept open on public transportation lines to curb the spread of the virus. This trolley sign urges people to keep windows open at home as well.

In 2020, many children are being homeschooled or receiving lessons online. But many schools remained open during the 1918 pandemic; like their grownup counterparts, children wore masks.

Buses were sprayed with anti-flu disinfectants.

At the influenza camp in Lawrence, Maine, patients were prescribed fresh air as a treatment.

Streetcar conductors and conductorettes (as female drivers were known) all wore masks to prevent infection. 

In October 1918, Boston mayor Andrew Peters invited news crews to come along as he received a flu shot.

Though thousands of Bostonians followed the mayor's lead, subsequent studies found no real evidence the vaccine had been effective.

In Paris in 1919, two men wore flu masks and advocated for others do the same.

These men at Camp Dix in New Jersey gargle with saltwater after a day's work at the camp.

Each day, women from the Department of War gathered for a 15-minute morning walk, in the hopes that the fresh air would ward off the flu.

The Boston Police Department distributed 1,700 masks to their officers to wear when they were on duty.

These Seattle policemen lined up in their gauze masks.

This hospital in Indiana had its own orchestra.

Before the internet, working remotely wasn't an option. This typist wore a mask while working at her office desk in 1918.

This telephone operator wears a gauze mask while working.

These New York City clerks sat in cramped quarters with their masks on.

Just like today, mail delivery was an essential function during the 1918 flu.

And the streets continued to be swept.

Here, a crossing guard is seen wearing a mask and gloves.

During any pandemic, nurses are on the front lines of the battle against disease.

Many people (mostly women) volunteered to join nursing groups to help battle the pandemic.

In 1919, these Red Cross nurses in Boston prepared bundles of masks to be distributed to soldiers. Meanwhile, other nurses were tasked with making the masks.

This is what a Red Cross mask-making station looked liked in 1918.

These volunteer nurses in Eureka, California tended to influenza patients at a Red Cross hospital in 1919.

This nurse is seen sterilizing a hospital room at the War Influenza Camp in Lawrence, Massachusetts.

The Red Cross assembled teams of volunteers to help fight the pandemic in the United States.

In Japan, these school girls wore their protective masks to guard against the influenza outbreak.

In October of 1918, months into the influenza outbreak, this crowd of war munitions workers in Washington D.C. gathered to drink hot chocolate near the Washington Monument.

Meanwhile, 20 miles away at Walter Reed Hospital, influenza patients were put in beds on the porch, separated by hanging sheets.

Women in New York City could be seen bundled in scarves and masks while out shopping.

The 39th Regiment marched through Seattle on its way to a deployment in France during the pandemic. Each soldier was outfitted with a mask provided by the Red Cross.

This outdoor Army hospital was constructed to house sick soldiers.

Here, a nurse pumps water at a makeshift influenza hospital.

The U.S. Navy set up this emergency camp outside of Mare Island Naval Hospital in Northern California.

This is what it looked like inside the Mare Island influenza ward.

Workers at the Navy's hospital at Fort Porter in New York wore masks while working.

These officers were in charge of the War Influenza Camp in Lawrence, Massachusetts.  

These volunteer nurses gather for a photo on the porch of the hospital in Eureka, California.

These female ambulance drivers help influenza patients injured in an explosion in New Jersey.

Red Cross workers inspected equipment at an emergency hospital at Wesleyan University in Middletown, Connecticut.

Nurses provide treatment to an influenza patient in New Orleans in 1918.

In 1918, San Francisco's Civic Center complex served as an emergency Navy flu hospital.

Here, President Woodrow Wilson (left) waves from a parade car after returning to the United States from France in 1918 at the end of World War I.