Russians on ice, Native Americans, Finland as bellwether for America, an anti-democracy riot, and one giant cool explosion.
1242: Russian forces led by Alexander Nevsky defeat the Teutonic Knights on the ice of Lake Peipus. 4,000 Teutonic Knights, mostly Estonians, are waging a "Northern Crusade" to convert Eastern Orthodox to Catholicism. After hours of hand-to-hand fighting, Nevsky unleashes his archers, and the western knights fall back further and further onto the ice fleeing. Eventually they start breaking through the ice and many drown. You would think the 1967 Dallas Cowboys would have learned from this, but as Santayana wrote, "Those who do not read history are condemned to repeat it and lose 21-17 to the Packers in 5 degree weather." (Germans also might have remembered this in 1941.)
1614: Pocahontas marries John Rolfe. She not only changes her last name, she changes her first name to Rebecca. In 1616 John decides they have to go home to meet the relatives. She is presented to court in London and attends a masque at Whitehall Palace. The couple starts to head back to Virginia, but she doesn't make it past Gravesend, where she dies and is buried. (She may have been a very literal-minded person.)
1932: Prohibition ends – in Finland. They've been making up for it ever since. For you future scenario planners out there, this is one data point for the hypothesis "As Finland goes, so goes the United States one year later."
1932: 10,000 rioters in St. John's, Newfoundland, sack the House of Assembly, demanding an end to "responsible" or democratic government. It couldn't happen here. You see, in response to real economic hardship, the democratically-elected legislature could not come to agreement as to how to remedy things, each side refused to compromise, and so the legislature became a bottleneck halting all progress. It's not a plausible future scenario for us, so don't worry.
1958: In one of the largest non-nuclear explosions in human history, Ripple Rock, a twin-peaked underwater mountain and menace to navigation in the approaches to Vancouver, British Columbia, is blown to smithereens on national television. At least 20 large and 110 smaller vessels had been sunk by the rock between 1875 and 1958. So 1,270 metric tons of Nitramex 2H are methodically pumped into deep shafts inside the underwater mountain for almost three years. When the plunger is hit at 9:31:02 AM, debris is sent 1,000 feet into the air, falling on land on either side of the miles-wide strait, and the channel's depth at low tide is now 45 feet (as opposed to the 9 feet it had been previously). And shipping is no longer threatened every time it approaches Vancouver. But let's face it, that was just an excuse. Blowing up an underwater mountain is just an awesome thing to do and I think we can all agree that this type of thing is exactly why, to quote Thomas Jefferson, "Governments are instituted among Men, deriving their just powers from the consent of the governed." (Key operative word "Men." I'm pretty sure men had the idea for this.)