As the flu pandemic tore though the United States in the fall of 1918, the city of San Francisco put all its faith in the power of masks to protect its citizens from getting sick. When officials briefly lifted the mask-wearing order and cases surged, that faith seemed well-placed.

The city had heralded the reprieve at noon on Nov. 21, 1918, by sounding sirens throughout San Francisco. Everywhere gauze squares fluttered to the ground as people cheered — but their glee was short-lived.

San Francisco Health Officer William C. Hassler soon informed Mayor James Rolph of a slight uptick in cases, and on Dec. 7, Rolph asked residents to mask up again. By January 1919, as the pandemic’s second wave hit the city, the request had become an order.

What happened next is echoed today, as Americans protest mask-wearing rules and enforcement during the coronavirus pandemic, calling them an infringement on their freedoms. Last week, a Family Dollar store security guard in Flint, Mich., was shot and killed after telling a customer that her child had to wear a face mask inside.

A century ago, a band of San Franciscans, led by several prominent business leaders and physicians, staged a rebellion. The Anti-Mask League held a public meeting on Jan. 25, 1919, that was attended by several thousand jeering residents demanding a permanent end to the city mask ordinance.

The gathering at the Dreamland Rink boxing arena devolved into a screaming match between moderates, who wanted to circulate a petition to rescind the ordinance, and extremists agitating to fire Hassler, before a booming voice announced an abrupt lights-out, according to historian Alfred W. Crosby, author of “America’s Forgotten Pandemic: The Influenza of 1918.”

City officials appeared to meet the protesters’ threats with calm resolve.

“What surprises me is that I have no requests from any others except the members of the Anti-Mask League who come here,” Rolph said, according to the minutes of the Jan. 27, 1919, Board of Supervisors meeting. “No petitions, no personal appeals have been made to me by anyone to hasten the removal of masks. To me the people of San Francisco are happy that the influenza is on the wane. I personally believe that the masks have had something to do with it.”

Hassler was regarded at the time as a bold and efficient public health leader. He had devised a registry of births and deaths after the 1906 earthquake and helped steer the city through outbreaks of the bubonic plague in Chinatown. Even so, he initially surmised that San Francisco’s cool, dewy climate would protect it from the flu. Then cases began climbing, from 169 on Oct. 9, 1918, to 2,000 a week later, according to the Influenza Encyclopedia produced by the Center for the History of Medicine at the University of Michigan.

Hassler decided that a short-term closure of businesses was necessary and, effective at 1 a.m. Oct. 18, the Board of Health voted to close movie theaters, dance halls and other entertainment venues, as well as all public and private schools, and prohibited social gatherings, according to the encyclopedia. But the city stopped short of enacting long-term sweeping quarantine measures like its neighbor to the south, Los Angeles.

The centerpiece of Hassler’s plan was a requirement that every resident wear a face mask, underscored by Rolph, who declared, “Whomever leaves his mask behind, dies.” The San Francisco Chronicle chimed in: “The man who wears no mask will likely become isolated, suspected, and regarded as a slacker.”

The vast majority of San Franciscans complied, sporting coverings ranging from the Red Cross gauze variety to flimsy chiffon affairs to elaborate creations resembling animal trunks.

Hassler himself wore a distinctive mask described by the Chronicle as a partially extended hard snout, “like the helmets affected by the French knights at the period of Agincourt,” but sheathed in gauze instead of metal. Never mind that we know now that these earlier mask incarnations did little good by themselves in preventing the flu’s spread. In San Francisco, they had become symbols of the wearer’s patriotism and contribution to the common good.

The city was not without scofflaws, however, and soon the $5 fines mounted, and the jails grew crowded. Many who broke the new law merely couldn’t be bothered, but some were more militant. One downtown lawyer argued that the mask ordinance was “absolutely unconstitutional,” and that police officers could be liable for enforcing it, according to the encyclopedia.

By the end of October, San Francisco had a total of nearly 20,000 cases of the flu and more than 1,000 deaths. Still, the numbers had briefly ticked down enough that the city decided to lift the mask law a few weeks later. As sirens screeched, residents ripped their masks from their faces and threw them in the air.

“The sidewalks and runnels were strewn with the relics of a torturous month,” the Chronicle reported.

When flu cases increased a few short weeks later, Rolph requested again that citizens don masks voluntarily, believing the measure by itself would be enough to quell the spread this time. But by early January, a second peak of influenza cases was sweeping the city, and the Board of Supervisors voted to reenact the mask ordinance.

By then, some San Franciscans had no intention of giving up their freedom again. One resident wrote Rolph that masks served no purpose but that Hassler alone could wear one if he wished. “And as far as I am concerned, I hope he will have to wear one for the next five years,” he said.

Despite Rolph’s determined remarks at the supervisors’ meeting on Jan. 27, the Anti-Mask League may have had some effect. On Feb. 1, the mayor rescinded the mask ordinance, proclaiming that the flu danger had sufficiently abated.

After the pandemic passed in the summer of 1919, leaving about 675,000 Americans dead in its wake, Hassler on more than one occasion crowed that his was the only big city in the world to have curbed the epidemic so successfully. But he was wrong.

In the final tally, San Francisco suffered about 45,000 cases of the flu and 3,000 deaths, considerably more than some other places of equivalent size. And researchers now surmise that by focusing so greatly on masks, Hassler may have unwittingly done San Franciscans a disservice. It didn’t help that face masks in those days were hardly N95s.

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