It's amazing the things you sometimes find on line while looking for other things ...
This, found on a site, appears to be taken verbatim from The Book of Lists by David Wallechinsky & Amy Wallace. I'll parcel out their second and third examples in the next few days. Perhaps some of us have further real-world examples?
Czarina Maria Fyodorovna once saved the life of a man by transposing a single comma in a warrant signed by her husband, Alexander III, which exiled a criminal to imprisonment and death in Siberia.
On the bottom of the warrant the czar had written: `Pardon impossible, to be sent to Siberia.'
The czarina changed the punctuation so that her husband's instructions read: `Pardon, impossible to be sent to Siberia.'