According to Isaac Newton, for any action, there is an equal and opposite reaction. Newton, of course, was talking about physics, yet any experienced historian will tell you that this concept applies to their field as well: one action — no matter how small — can literally change the world. These figures may not have realized it in the moment, but their last-minute decisions singlehandedly altered the course of history.
One of the leading faces of the American civil rights movement, Martin Luther King Jr. is fondly remembered for his "I Have A Dream" speech, delivered in front of the Lincoln Memorial in 1963. Unbelievably, MLK improvised the speech on the spot, completely abandoning his notes after one gospel singer asked him to tell the audience about his "dream."
Always bring binoculars
Astonishingly, the tragedy of the Titanic could have been avoided if not for one change in staff. When Second Officer David Blair was removed from the crew, he forgot to hand in his key to the locker that housed the lookout binoculars. As a result, the crew relied on their own eyesight to spot danger ahead, a contingency plan that proved catastrophic.
A costly carriage
Infamous for her ignorance, Queen Marie Antoinette was one of the main causes of the French Revolution, as her lavish lifestyle infuriated the struggling working class. Ultimately, this vanity led to the death of her family. Instead of fleeing in a regular carriage Marie demanded a fancier one for her escape, which proved to be slower and allowed the mob to catch up to them.
Change of plans
Following the attack on Pearl Harbor, the United States vaporized the Japanese cities of Hiroshima and Nagasaki with atomic bombs. Initially, America wanted to bomb Kokura, though a young crewman named Kermit Beahan insisted it was too cloudy to see the entire city. What turned out to be a lucky break for Kokura became a tragedy for Nagasaki, the next target on the list.