In the early 1990s, the country of Rwanda struggled through growing tensions between the local ethnic groups, the Hutus and the Tutsis. The Hutus led the government, while the Tutsis were targets of harrassment and discrimination. Over the course of a hundred days in 1994, those tensions would erupt in fear, violence, desperation, and genocide.

Some plane crashes have possible causes which are so out of the ordinary they stretch the limits of credulity. The accident which happened when a plane fell from the sky while attempting to land in the Democratic Republic on the Congo in 2010 is just such a crash.

The black servicemen who loaded munitions onto ships at Port Chicago Naval Magazine knew it was only a matter of time before the inevitable happened. They were hardly trained, rushed to load ships heading for the Pacific theater in World War II, and feared every day that this might be the day one dropped bomb blew them all to smithereens. On July 17, 1944, Port Chicago's number finally came up. But the tragedy which occurred there was not the end of the story. 

He was a teacher and a veteran. On August 20, 1982, an argument over a badly repaired lawnmower motor from the previous day would result in a massacre which left eight dead.

Sometimes when planes crash, it's due to the tiniest hidden flaw which causes incredible amounts of destruction after a series of one mishap after another. One microscopic flaw led to the failure of the tail-mounted engine on a DC-10, and the damage it caused ended with an incredible fiery crash caught on camera.

In wartime, terrible loss of life is expected - but usually not due to a series of ridiculous screw-ups. On January 31, 1918, a fleet from the British Royal Navy left a Scottish port in the Firth of Forth with the intention of leaving for exercises in the North Sea. But among that fleet were multiple K-class submarines, a sub notorious for its flaws, its bad luck, and its short history of deadly accidents.

Working on an oil rig in the North Sea has its frustrations, its problems, and its dangers. In July of 1988, employees on the Piper Alpha platform were looking forward to having to work around construction as problem areas in the rig were updated - paint to be applied, sprinkler heads to be unclogged, and a broken safety valve to be fixed and replaced. In the end, a series of lapses and mistakes would lead to the deadliest oil rig disaster in history.

In most cases, we can trust the ground beneath our feet. We expect it to be solid, to hold firm, and to not move when we stand on it. Some places we can expect earthquakes, but most of the time we don't expect to look out the window and see the very land we've gotten used to outside every day slamming down toward our homes.

When someone says a mass shooter was "going postal," the term goes back to a series of workplace shootings in the United States postal service going back to the mid-1980s. The deadliest of those took place in Edmond, Oklahoma, when an unsettling middle-aged man walked into work on August 20, 1986, with three guns in his mailbag.