In the days of sail, conquest and exploration, it was necessary to carry fresh water on board ship for officers and crew. The only problem was that the water did not remain fresh. Stored in casks, it developed algae and became slimy. Accordingly stagnant water was mixed with beer and wine to make it sweeter and more palatable. As voyages became longer, greater amounts of water needed to be stored.
Following Britain’s conquest of Jamaica in 1655, a daily ration of rum replaced beer and brandy rations but some sailors saved their rations and drank them all at once, leading to illness and lack of discipline. In 1740 Admiral Edward Vernon (above) ordered that water be added to the rum to dilute it. Subsequently Vernon also ordered that lemon or lime juice be added. Although it was not then known that citrus fruits assisted in preventing scurvy, it was known that Vernon’s sailors were healthier than others.
Admiral Vernon was in the habit of wearing a grogram coat, being a coarse fabric of silk mixed with wool or with mohair and often stiffened with gum. From this he became known to the sailors as “Old Grog”.
Vernon’s insistence on watered brandy, with citrus, was not popular. The expression was that compared to the previous drink, it was "as thin as Old Grog's cloak.”
From 1756 sailors in the Royal Navy were issued a half pint of rum mixed with one quart of water, split into two servings, one before noon and one after the end of the working day. The rum ration, part of the regulations, lasted until discontinued in 1970.
And by the way, the famous quotation:
"Don't talk to me about naval tradition, it's all rum, sodomy and the lash."
was not spoken by Winston Churchill, although it is commonly attributed to him. The words were spoken by Churchill's assistant, Anthony Montague-Browne, who later said that although Churchill had not uttered these words, he admitted that he wished he had