Ahh, spring — that magical time when it isn’t as warm as you desperately need it to be, and when that last surprise snowstorm has us accusing meteorologists of fraud.

But sometimes, weird weather can be a boon, particularly when it comes to the existence of one United States of America. Here are three times when the movements of the heavens helped Americans here on earth.

The fog of (Revolutionary) war

On the face of it, it may not look like America was “saved” during the Battle of Long Island; Gen. George Washington and the Continental Army he commanded lost badly. They were outnumbered by the British 2 to 1. One-fifth of Washington’s force had been lost to death, injury or capture. And on the evening of Aug. 29, 1776, they were pinned down in Brooklyn between the East River and the British army.

Though rain had ruined Washington’s earliest military pursuits, on this night, Mother Nature did him a solid — in the form of liquid and gas. First, rain slowed down the British advance. That gave Washington time to plot an escape. As the sun went down, Washington gathered every boat available to the shore and began to — very quietly — evacuate his men across the shore. As Ron Chernow describes in “Washington: A Life,” cloth was wrapped around oars to mute their sound, and winds miraculously shifted so sailboats could silently glide across the river. Washington ordered campfires to stay lit all night to trick British guards into thinking they hadn’t moved.

But they still weren’t fast enough to beat the sun, which, in these pre-daylight-saving years, rose at about 5:20 a.m. Dozens of men were still waiting to leave, including Washington, when a glorious fog rolled in. It was so thick, one soldier reported, that you couldn’t see more than 20 feet away. That was all the Americans needed to evacuate the rest of their troops. Washington was the last one to board a boat to safety, and he and his army were free to fight another day.

The singeing of Washington

Frequently, when an invading army captures a city, they occupy it. (For example, when Washington’s troops evacuated New York, the British occupied it for seven years.) But not so when the British invaded Washington during the War of 1812.

Why? The weather, probably.

Sure, when the British invaded on Aug, 24, 1814, they set the Capitol building on fire — which at the time housed not only Congress, but the Supreme Court and the Library of Congress. Then they set the White House alight, famously sending first lady Dolley Madison running (though not with a painting in hand, as you may have heard).

The next morning, with the previous day’s fires still smoldering, British troops continued their arson. And that’s when a severe thunderstorm, possibly a hurricane, came barreling in. A pounding rain put all the fires out. Wind sent debris flying, killing several British soldiers. Then a tornado touched down in the middle of Constitution Avenue, sending cannons into the air, which landed right on top of them.

Terrified British troops regrouped on Capitol Hill and decided to bail. The wind and rain continued, and as they headed for their damaged ships to sail away, a British admiral exclaimed to a resident: “Great God, Madam! Is this the kind of storm to which you are accustomed in this infernal country?”

Some historians say the British never intended to occupy the city, only to raze it; others disagree. In any case, they were in and out in 26 hours, and the incident soon became known as “the storm that saved Washington.”

Longstreet’s silent charge

Heading into the Battle of Gettysburg in July 1863, Confederate Gen. Robert E. Lee was aiming for a decisive win, one so big it would drive the Union to seek peace terms. Among Lost Cause apologists, Lt. Gen. James Longstreet is the villain whose dawdling foiled that plan.

But, according to one theory, a bizarre phenomenon known as an “acoustic shadow” may have played a bigger role in the defeat.

As the summer heat bore down on the second day of fighting, Lee ordered Longstreet to attack Union troops at Cemetery Hill and take the virtually empty Little Round Top. Lt. Gen. Richard S. Ewell’s men were to make a show of force opposite them to split the Union troops and draw them away from the hill. Ewell was to begin his action at the sound of Longstreet’s artillery barrage.

Yes, Longstreet did take a long time to gather his men before attacking in the late afternoon. But, according to physicist and military expert Charles D. Ross, “for a long time after Longstreet had begun his attack, Ewell heard nothing and hence did not move his troops.” When the fighting that day was over, Longstreet’s men were narrowly defeated, and the Union had yet another high tactical advantage.

So why didn’t Ewell hear Longstreet’s barrage? According to Ross, Ewell was likely in the middle of an acoustic shadow, an atmospheric phenomenon caused by a combination of geography, heat and wind by which sound is “stopped” from traveling in one direction, even while it travels perfectly well in others.

The hillsides of Gettysburg are just the sort of place where acoustic shadows can develop. “More importantly, the hot temperatures near the ground probably caused a dramatic upward refraction of sound waves,” wrote Ross.

The next day, when Maj. Gen. George Pickett went on his doomed charge, his men were cut down by Union troops positioned perfectly on Little Round Top, the very place Longstreet had barely lost. From then on, the Union had the upper hand in the Civil War.

Because of this and other acoustic shadows during the war, Ross wrote, “One might even go so far as to say the acoustical shadows determined the course of the entire war.”

Dig deeper: Weather + History

Want to explore how extreme weather has impacted history? Check out our curated list of stories below.

Mother Nature gave George Washington an assist in winning the Revolutionary War.

The National Hurricane Center started officially naming hurricanes in 1950. The naming system remained largely unchanged until 1979, when men’s names were introduced into rotation.

Scientists say that without seasons, not only would there would be less variety in plant and animal life, but it’s possible life wouldn’t exist at all.

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