Friendly fire

The use of airplanes in WW2 went up. They were used for reconnaissance, bombardment, supply, dogfights and... based on this picture, friendly fire. Aviation played a key role in the war. First it was the Luftwaffe which utilized it for their Blitzkrieg tactics. After that, airplanes had a crucial role in the Battle of Britain where the UK and German air force collided.

BLUE ON BLUE. 

Soon enough the Soviets, Americans, Japanese... everybody was racing to make the better fighter or bomber. There were crazy aircraft models being produced: jet fighters, plans for world-wide-bombers which could drop nukes on the other side of the globe, submarines with airplanes... In the end, the Allies prevailed in the skies since the Axis supplies were running thin and they couldn't keep up with the production and aviation financing.

1906 San Francisco earthquake aftermath

The SF earthquake of 1906 is considered to be one of the worst natural disasters in the US. Almost 80% of SF was destroyed from the earthquake and fires. Oh and about those fires, well, it was a war zone... Bunch of people were insured in case a fire happens, but not many were insured against an earthquake. So people, being in fear of insurance not covering their earthquake damaged houses, did the next most logical thing - they set their houses on fire.

If you're going to San Francisco...

One fire was so great that they had to blow up chunks of buildings (literally stack TNT in a place) around a few city blocks so they would collapse and stop the fire from spreading. They even used artillery. Soon enough, the army moved in to help and they kinda stopped the looting and helped people. They even shot men who were trapped on rooftops and wanted to jump. All in all, a 10/10 tragedy.

Stock market crash

I never fully understood the stock market. You have a bunch indicators, buying, selling, people yelling around, movies being made about it, people tripping... about it. But throughout it all there's a strange feeling related to it, something like gambling, even though it's a "science" and you need to know your shit.

That's what you get for speculating being stupid.

Anyway, a bunch of old men in suits got together one day to buy and sell stock while smoking indoors. This lead to the Wall Street Crash of 1929 ushering the era of Great Depression. It was a huge change from the "roaring twenties" where people would spend money and party like there's no tomorrow.