Eclipses are gripping events. Scientists study them. Others view them in wonder, or fear. Here are four eclipses that influenced events in unexpected ways.

Downfall of Athens – lunar eclipse August 28, 413 BCE
Athens and Sparta were major powers locked in a struggle for control over what is now Greece. When the Athenians became convinced that the main Sicilian city Syracuse threatened their allies in Sicily, they sent an expeditionary force. Besides neutralizing the threat, conquering Sicily would greatly increase their resources.

The expedition went badly. Sparta sent help to Syracuse, and the Spartans and Syracusans successfully held off the invasion. Nicias, who led the Athenian forces, sent for reinforcements, but even when most of the Athenian fleet was present, they were still losing. A strategic retreat was in order.

As the Athenians were ready to withdraw, a lunar eclipse occurred. Nicias, being very superstitious, consulted the priests. They suggested waiting for another 27 days, and – fatally – he did. The eclipse was certainly not a bad omen for Syracuse. They and their Spartan allies attacked the Athenians, taking or destroying all their ships and slaughtering or enslaving their soldiers. Athens never recovered from this loss, and eventually lost the war with Sparta.

Slave Rebellion – solar eclipse and bluish Sun
Nat Turner was a slave in early 19th century Virginia. He was educated, literate, intelligent, and convinced that he had a prophetic mission to free the slaves.

Turner saw an annular solar eclipse on February 12, 1831, and interpreted it as a sign that he should prepare for a rebellion. He originally planned his uprising for Independence Day, but had to postpone it for various reasons. Then on August 13, the Sun appeared to be a blue-green color. This looked like a strong reminder to get on with the struggle. The rebellion started a week later.

We don't know what caused the Sun's strange color, but Mt Saint Helens in Washington was erupting around that time, and there were forest fires in Virginia. The smoke and dust from either could cause a blue Sun.

Columbus saved – lunar eclipse March 1, 1504
In 1503 Columbus made a fourth voyage to what he still insisted was Asia. It ended up with his ships damaged and him stranded in Jamaica. At first he was welcomed by the locals. However the sailors, instead of being grateful, behaved so badly that the people refused to feed them anymore. This seems justified to me, but it was hard on Columbus.

Yet all was not lost. Columbus had an almanac and an idea. The almanac had eclipse times for the years 1475-1506, calculated by the great German astronomer and mathematician Regiomontanus (1436-1476). And a lunar eclipse was coming up.

Columbus announced that his god was angered by the poor treatment he and his men were getting, and would be manifesting his ire through a Moon “inflamed with wrath”. On the predicted night, the Moon rose already partly eclipsed, then darkened until it was a dull red orb. Not surprisingly, this terrified the locals. They begged Columbus to intercede for them, promising the supplies that he needed. He spent some time in his quarters, timing the eclipse, finally emerging to announce that his god had relented, and that the Moon would be restored. As indeed it was.

King of Siam's Eclipse
Was helium discovered on the Sun during the eclipse of August 18, 1868? Not exactly, but there's a link between the eclipse and the gas.

French astronomer Pierre Janssen, who viewed the eclipse in Madras, India, wasn't as engrossed in the eclipse as he was in devising a way of studying solar prominences when there was no handy eclipse. During the eclipse he noticed a very bright line in the Sun's spectrum, and he used it to continue his observations after the eclipse.

English astronomer Norman Lockyer hadn't seen the eclipse, but was working independently on solving the observing problem. Both astronomers were successful in their endeavors and sent reports to the French Académie des Sciences, Janssen from Madras and Lockyer from London. Amazingly, the reports arrived in Paris on the same day. The Academy decided to cast a medal giving them joint credit for this useful innovation.

Janssen wasn't interested in the identity of the bright line he'd seen, but when Lockyer saw it, he was intrigued enough to study it further. He thought that it might represent an element unknown on Earth, and provisionally called it helium (from helios, Greek for Sun), but didn't publicize his speculations. The element was discovered on Earth many years later when William Ramsay isolated it in the laboratory. Only then could it be shown to be the element whose spectral line was seen on the Sun.

This eclipse is sometimes called the King of Siam's Eclipse, because in Siam (today's Thailand) a quiet revolution was taking place. King Mongkut was bringing social and educational reform to his country, keen that it be seen as progressive. He was highly educated and knowledgeable both about traditional Buddhist astrology and astronomical measurement. The King worked out the timing of the 1868 solar eclipse and the best place to view its totality in Siam. He invited his own and European officials to observe it with him.

On the positive side, it was an impressive demonstration of modern Siam. Sadly, the king and Prince Chulalongkorn contracted malaria on the expedition, and the king died six weeks later. However the prince recovered and continued the reforms. This may have saved Siam from being occupied and “civilized” by colonial powers.