JMB added the thumb safety specifically to allow the 1911 to be carried with a round in the chamber cocked and locked. Here is the description from the August 19, 1913 patent.
Heretofore pistols of this class were provided with automatic safety devices which made it impossible to fire one or...
Good article thank you!
Colonel Cooper may have come up with the term Condition One but John Moses Browning described it in his final patent for the 1911 (August 1913) when he gives the reason for adding the thumb safety.