1780: In the midst of the Revolutionary War, darkness descends on New England at midday. Many people think Judgment Day is at hand. It will be remembered as New England's Dark Day.

Diaries of the preceding days mention smoky air and a red sun at morning and evening. Around noon this day, an early darkness fell: Birds sang their evening songs, farm animals returned to their roosts and barns, and humans were bewildered.

Some went to church, many sought the solace of the tavern, and more than a few nearer the edges of the darkened area commented on the strange beauty of the preternatural half-light. One person noted that clean silver had the color of brass.

It was darkest in northeastern Massachusetts, southern New Hampshire and southwestern Maine, but it got dusky through most of New England and as far away as New York. At Morristown, New Jersey, Gen. George Washington noted it in his diary.

In the darkest area, people had to take their midday meals by candlelight. A Massachusetts resident noted, "In some places, the darkness was so great that persons could not see to read common print in the open air." In New Hampshire, wrote one person, "A sheet of white paper held within a few inches of the eyes was equally invisible with the blackest velvet."

At Hartford, Col. Abraham Davenport opposed adjourning the Connecticut legislature, thus: "The day of judgment is either approaching, or it is not. If it is not, there is no cause of an adjournment; if it is, I choose to be found doing my duty."

When it was time for night to fall, the full moon failed to bring light. Even areas that had seen a pale sun in the day could see no moon at all. No moon, no stars: It was the darkest night anyone had seen. Some people could not sleep and waited through the long hours to see if the sun would ever rise again. They witnessed its return the morning of May 20. Many observed the anniversary a year later as a day of fasting and prayer.

Professor Samuel Williams of Harvard gathered reports from throughout the affected areas to seek an explanation. A town farther north had reported "a black scum like ashes" on rainwater collected in tubs. A Boston observer noted the air smelled like a "malt-house or coal-kiln." Williams noted that rain in Cambridge fell "thick and dark and sooty" and tasted and smelled like the "black ash of burnt leaves."

As if from a forest fire to the north? Without railroad or telegraph, people would not know: No news could come sooner than delivered on horseback, assuming the wildfire was even near any European settlements in the vast wilderness.

But we know today that the darkness had moved southwest at about 25 mph. And we know that forest fires in Canada in 1881, 1950 and 2002 each cast a pall of smoke over the northeastern United States.

A definitive answer came in 2007. In the International Journal of Wildland Fire, Erin R. McMurry of the University of Missouri forestry department and co-authors combined written accounts with fire-scar evidence from Algonquin Provincial Park in eastern Ontario to document a massive wildfire in the spring of 1780 as the "likely source of the infamous Dark Day of 1780."

Source: The Weather Doctor