I found this hilarious Q & A buried in the archives of the Chicago Manual of Style online:

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Q. About two spaces after a period. As a US Marine, I know that what’s right is right and you are wrong. I declare it once and for all aesthetically more appealing to have two spaces after a period. If you refuse to alter your bullheadedness, I will petition the commandant to allow me to take one Marine detail to conquer your organization and impose my rule. Thou shalt place two spaces after a period. Period. Semper Fidelis.

A. As a US Marine, you’re probably an expert at something, but I’m afraid it’s not this. Status quo.

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I’m a diehard two-spacer.  Abusus non tollit usum.