November 12 was the birthday (in 1864) of Admiral Edward Vernon. Vernon was known as “Old Grog” by his crew, due to his frequent use of grogram (coarse-textured wool fabric) cloak or breeches.
In 1740, he began watering down his sailors’ rum in order to reduce drunkeness and the physical damage that ensued. The diluted rum, in turn, took on Vernon’s nickname, grog.
And now you know.
(from the Forgotten English calendar by Jeffrey Kacirk)