The military veterans, gathered to celebrate the nation's bicentennial, had made it through World War I, World War II, Korea or Vietnam, only to be struck down by the mist from a hotel's air-conditioning system.
It was the first time the world would learn of potentially deadly bacteria that cause a severe form of pneumonia, later to become known as Legionnaires' disease.
A total of 221 people staying at the Bellevue-Stratford Hotel in Philadelphia, most of them veterans attending a Pennsylvania American Legion bicentennial convention, were sickened by the water-borne germ, and 34 of them died.
That 1976 tragedy remains a deeply personal memory, a key moment in my journalistic career, and this past week there was news about the latest Legionnaires' disease outbreak, this time linked to the mist from a Lehigh Valley medical facility's decorative fountain.
A half-dozen people who had visited the Integrated Health Campus in South Whitehall Township, it was reported, came down with Legionnaires' disease. The Pennsylvania Department of Health asked medical people to be on the lookout for more victims who had visited the facility.
The decorative fountain in the lobby of an IHC building was shut down and drained, as was another outside fountain. Tests of the water were pending. The story noted the bacteria, now called Legionella, are mainly found in water and are especially dangerous to the elderly, smokers and people with weakened immune systems.
In 1976, the late Ed Houck, then the adjutant of the state American Legion, became alarmed when he started hearing about fellow veterans coming down with pneumonia after attending the July 21-24 convention at the Bellevue-Stratford.
Houck and I knew each other quite well in those days, when I was at the Associated Press bureau in Harrisburg, and he said he was calling "to ask for some advice."
Was there some way, he asked, that he could get a small notice published in newspapers, telling veterans who became ill after the convention to be sure to seek medical help? He said he was even thinking about buying a few little ads.
That is how the Legionnaires' disease story began, and I was the reporter who broke it, thanks to Houck.
Many of Houck's fellow American Legion members had become ill, he told me, and the first death came in Bradford County three days after the convention ended. Three days after that, four more were dead in various parts of the state. All had one thing in common — the Bellevue-Stratford.
By the time Houck told me that, I was already banging away at my typewriter at the AP office inside the state Capitol building. The era of Legionnaires' disease began at that moment, although it was later determined that the bacterium had been around long before 1976.
A day after that AP bulletin, the deadly outbreak was the top story in just about every newspaper in Pennsylvania, and soon across the nation. It was the top cover story in both Newsweek and Time.
Around the same time Houck called me, a physician in Bloomsburg had three very ill patients, and he learned that all three had attended the American Legion convention in Philadelphia. He contacted the Pennsylvania Department of Health, which began looking into a possible link, so it's likely there would have been a fuss even without my story, but the AP got credit for getting the word out first.
The Health Department soon got the U.S. Centers for Disease Control, based in Atlanta, involved in efforts to figure out what was causing the illness, and the CDC began an intense nationwide probe.
Some American Legion people were angry with me, not because I broke the story, but because they blamed me for naming the disease after their organization.
Actually, the name of the disease was suggested by a physician working with a special committee set up by national American Legion officials, and it was the American Legion itself that asked the CDC to officially call it Legionnaires' disease.
Since the Philadelphia outbreak in 1976, there have been dozens of outbreaks all over the world. The Philadelphia death toll is still the record for any single episode, although the Netherlands came close in 1999 when 32 people died.
Almost all of the Legionnaires' disease cases have involved water, often the water-cooled portions of large air-conditioning systems, such as the cooling pool on the roof of the Bellevue-Stratford. Some have been traced to decorative fountains, such as the case in South Whitehall.
There was one other personal component for me.
I always loved the Bellevue-Stratford and felt terrible when the news stories of 1976 resulted in its being shut down just four months after the outbreak. This hotel was famous for lodging most of the presidents and other luminaries who visited Philadelphia through the 20th century, but our stories all but destroyed it.
The hotel reopened in 1979 and has bounced from name to name since then, closing again in 1986 after a $100 million renovation and then reopening in 1989.
The venerable old building is still there and is still in use, however. Legionnaires' disease cannot claim it as a victim.
Paul Carpenter's commentary appears Sundays, Wednesdays and Fridays.