William III's equestrian accident is commonly attributed to his horse tripping on a molehill. The King broke his collarbone in the fall; as a consequence he contracted pneumonia, and this proved fatal.
Ironically, the horse (named Sorrel) had been confiscated from Sir John Fenwick, one of the Jacobites who had conspired against William. Fenwick had been executed in January 1697 (five years before William's death).
On one blog I found, someone made the pertinent comment that "It is far more likely that William's horse tripped on a ant–hill built by the yellow meadow ant, than on a molehill. Molehills are friable, easily dispersed, and hardly occur at all in Richmond Park, whereas ant–hills have their surfaces matted with vegetation, last for tens of years, and are clayey." Wikipedia resolves this conundrum by specifying the cause of the stumble as the mole's burrow, rather than a molehill.
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