The men who fell ill on August 27^th were among 7,000 sailors living at the huge, crowded barracks on Commonwealth Pier while waiting to ship out. In these conditions, the virus spread with ease. On the 28^th, eight new cases appeared; four days later, 106. While most of the men were suffering from the fever, cough, and aches that usually accompany the flu, 10 to 20% had symptoms that often proved fatal — high fever, chills, vomiting, delirium, blood spurting from the nose, eyes, and ears. Autopsies on patients who died within 48 hours of contracting the disease revealed lungs so full of blood that they sank when placed in water.

There were two waves of the 1918 pandemic. While highly contagious, the first wave brought a mild and forgettable disease that began in Spain in February. The Boston outbreak was the beginning of the second and deadlier wave, which would kill millions of people around the world. No disease in human history — including the Black Death (1347-1350) — caused so many fatalities.

At first the fact that a highly infectious, deadly disease was spreading went almost unnoticed. The Boston Globe stated that doctors had the flu "pretty well in hand" on September 13^th, the same day the Navy reported 163 new cases. At Fort Devens, an army base 30 miles west of Boston, 12,604 cases were recorded in just two weeks; in Boston, children jumped rope and sang:

"I had a little bird

And its name was Enza

I opened the window and

In-flew-enza."

While the public was slow to realize the danger, the situation was increasingly grim. The hospital at Fort Devens, built for 2,000 patients, struggled to accommodate 8,000. The U. S. Surgeon General was sufficiently concerned to send Colonel Victor Vaughan, a respected epidemiologist, and Dr. William Henry Welch, the dean of American medicine, to the base. Vaughan described a terrible scene: "Every bed is full, yet others crowd in. The faces wear a bluish cast; a cough brings up the blood stained sputum. In the morning the dead bodies are stacked about the morgue like cord wood." The usually unflappable Welch was alarmed, too. "This must be some new kind of infection," he said after observing an autopsy. "Or plague."

By late September, nearly 50,000 people in Massachusetts had the flu, and the illness was spreading rapidly to other parts of the nation. The situation was so dire that the Army canceled a draft call despite the fact that it badly needed more soldiers in Europe.

Overwhelmed public officials did their best to contain the disease. In Philadelphia, which was particularly hard-hit, health officials campaigned against coughing, spitting, and sneezing. Other communities took more desperate measures. In Prescott, Arizona, it was illegal to shake hands. San Francisco required residents to wear gauze masks —completely ineffective against the microscopic virus — and police arrested people who did not comply.

Where did such a virulent strain of influenza come from? Rumors and theories abounded: The germs were inserted into aspirin made by the German company Bayer. A camouflaged German ship had released them in Boston Harbor. Germans sneaked ashore and let loose vials of germs in theaters and other large crowds. The health commissioner of Denver had a novel explanation; he blamed the city's Italian immigrants.

Physicians searched frantically for a vaccine to prevent the flu and for ways to treat the symptoms. Medical authorities even conducted tests on volunteers at a military prison on Deer Island in Boston, promising pardons to those who survived the experiments. Ultimately, all such efforts were unsuccessful. There was nothing to be done except keep patients hydrated, rested, and warm. Researchers would not identify the virus that caused the outbreak until the 1930s, long after the epidemic had ended.