On this day in 1976, members of the American Legion arrive in Philadelphia to celebrate the bicentennial of U.S. independence. Soon after, many began suffering from a mysterious form of pneumonia. Their ailment would come to be known as Legionnaires disease.
About 4,000 delegates from the Pennsylvania chapter of the American Legion met at the Bellevue-Stratford Hotel in Philadelphia for a four-day gathering. While at the hotel, built in 1900, the Legionnaires did not notice anything unusual. However, several days after the event ended, many attendees became sick. By August 2, 22 people were dead and hundreds connected to the gathering were experiencing pneumonia-like symptoms.