This marks the day ol' Columbus set out in 1492.  A day fraught with both peril and profit.

and in 1583 Sir Humphrey Gilbert landed at Newfoundland and planted the English Flag. in effect the first English colony in North America.

in 1776, this is the day the delegates actually signed the enlarged presentation version of the Declaration that is preserved.

in 1865 in the North Pacific, the commerce raider Shenandoah was cruising Alaskan waters sinking American flagged whalers when it encountered a British vessel that had news of the April Surrender and Collapse of the Confederate Government.  It's commander, Waddel, performed the near miraculous feat of sailing his vessel from Alaskan waters, around Africa, and up to Portsmith England without once touching land... to surrender his vessel to the British.

1876 Wild Bill Hickok was shot dead, in ambush, while playing poker, his putative final hand: Aces and Eights, is called a "Deadman's Hand" to this day.

Germany declared war on France in 1914

1923 Warren G Harding collapsed and died on the return voyage from Alaska.

1958 Nautilus dipped below the polar ice cap; a nuclear sub first!

So today is kind of a big day for starting big things in world History.