a small event that changed history?

Here's an interesting quote from a Freedom Trail guide I bought yesterday about an event at the Old South Church:

On March 6, 1775, Dr. Joseph Warren delivered an oration "perpetuating the memory of the horrid massacre" [i.e. the Boston Massacre] on its fifth anniversary. Again thousands of people packed the meeting-house, so tightly that Warren had to climb in through a window.

Legend has it that a British ensign was planning to throw an egg at Warren at the first sign of treason. In the ensuing confusion, all of the town's leading patriots -- including Warren, [Sam] Adams, and Hancock -- were to have been arrested. It was a wonderful plan, except for one thing. The ensign fell on his way to the meeting, breaking his leg (as well as the egg), and he never showed up.

Although the book says it's only legend, I bet there's some truth to it. Pretty funny and interesting, and also a reminder that small events can have a great impact on history.