Top 10 biggest blunders in history

Blunder: Landlubber left all at sea
Cost: The Spanish Armada is crushed
In 1588, Philip II of Spain decided to send his mighty Armada to attack England. As his long-term admiral had recently died, the King put the Duke of Medina-Sidonia, an army man with negligible naval experience, in charge of his 130-vessel-strong fleet.

Despite the Duke’s own protests, he ended up leading 27,000 men into battle. His lack of experience ranks pretty highly among the reasons for the Armada’s failure.

Blunder: Going against the Emperor – albeit unknowingly
Cost: A Roman senator takes his own life
Everyone’s favourite tyrannical Roman Emperor, Nero, went through a phase of dressing in disguise, taking to the streets with his mates and starting fights. On one such rampage c56 AD, he picked on a senator named Montanus, who put up a fight and left Nero black and blue.

The victor later realised who his opponent was and sent a note of apology to the Emperor. It was a polite yet idiotic gesture as that note was the incriminating evidence for his treason. He swiftly took his own life.

Blunder: Sharing too much
Cost: £190 million on the stock market
In 2005, a Japanese trader made a stock-market slip up that lost Mizuho Securities a cool £190 million. Instead of selling one share of a manpower recruitment firm at 610,000 yen, he sold 610,000 shares for one yen (0.5p). Despite the investment bank’s numerous attempts to block the sale, the disastrous deal went through.

Blunder: Is it a strong military position, or a steaming crater?
Cost: Burnside loses his reputation, men and job in one day
Among his many failings as a commander of the Union army in the American Civil War, arguably General Ambrose Burnside never demonstrated his ineptitude more than at the Battle of the Crater in July 1864.

As part of the siege of Petersburg, Virginia, his forces blew up a mine beneath the Confederate defences, killing 352 Southern soldiers. He then sent his units charging into the smoking crater, where they could do little but dither about as easy targets. The Union army suffered 3,800 casualties to the Confederates’ 1,200, and Burnside was quickly out of a job.

Blunder: NASA screws up its sums
Cost: A $125 million satellite
NASA’s Mars Climate Orbiter was supposed to be the first weather observer on the red planet but, on 23 September 1999 (nine months after blast off), communication abruptly ended. It turned out that, while one team had used pounds-seconds for the craft’s complex calculations, another used the metric units of Newton-seconds. The result was the $125 million Orbiter going too close to the planet, and disintegrating in the upper atmosphere.

Blunder: Making Genghis Khan angry
Cost: End of the Khwārezm Empire
When, in c1218, the Mongol warlord Genghis Khan sent a caravan of 500 emissaries to the neighbouring Khwārezm Empire, the Shah, Alā’ ad-Dīn Muhammad, made the interesting decision to have them all arrested.

A second party of three ambassadors was despatched to speak with the Emperor directly, but the Shah had them decapitated. Quick to anger, the vengeful Genghis Khan marched on his enemy with 200,000 men and, within two years, the Khwārezm Empire was no more.

Blunder: Pricey birthday present
Cost: German advantage in WWII
German field marshal Erwin Rommel, entrusted with defending north-west France from Allied attack, must have felt pretty confident in June 1944, because, with his wife’s birthday coming up, he popped home to see her. Unfortunately, that just so happened to be exactly when the Allies launched history’s largest sea-borne invasion – D-Day.

Blunder: Letting the wrong ones in
Cost: Constantinople falls
For centuries, Constantinople (now Istanbul) was a fierce stronghold but in 1453, the Byzantine capital finally fell. Why? Well, after 53 days being besieged by the vast Ottoman army, someone left a gate unlocked (it could happen to anyone). As the Ottomans poured through the wall, all hell broke loose as soldiers and civilians were slaughtered alike, and 30,000 were enslaved.

Blunder: Cross-breeding comes with a sting
Cost: African ‘killer’ bees at large
Brazilian scientist Warwick Kerr began cross-breeding species to develop the Africanised bee in the 1950s, in the hope of increasing honey production. But that was only the bee-ginning. When, in 1957, 26 swarms were accidentally released into the wild by a temporary beekeeper, it was discovered that Kerr’s Africanised bees were quite the murderous little invertebrates. Forming super-aggressive swarms, they have – so far – killed some 1,000 people across the Americas.

Blunder: No one at the CIA could tell the time
Cost: Failed invasion of Cuba, almost 1,200 paramilitaries captured
The CIA’s strike on Castro’s Cuba, at the Bay of Pigs in 1961, was a total embarrassment for the US. Like a matryoshka doll, the short-lived conflict contained many smaller fiascos. Perhaps the most groan-worthy came when six bombers arrived for a mission on day three an hour late – apparently those in command hadn’t factored in the time difference between Nicaragua and Cuba.