awrence Washington, George's older half-brother, was commissioned a captain in the Colonial Marine Corps in 1740 and served under British Admiral Lord Edward Vernon. In 1739, England had declared war with Spain due to Spanish piracy of English shipping.

For the next three years, “American” Marines fought aboard British ships in the Caribbean where they captured Spanish cargo. Lawrence's share of the prize money during his service enabled him to purchase a large plantation that he named Mount Vernon, in honor of his former commander. Upon Lawrence's death, Mount Vernon passed to George.

Of further note: Admiral Vernon's nickname was “Old Grog” after the grogram (wool and silk blend fabric) cloak he wore on the bridge in foul weather. During one cruise, Vernon's fleet ran out of beer-a very serious matter since British Naval regulations promised each sailor a ration a day.

“Old Grog” substituted Jamaican rum, which the sailors took to at once. But then the Admiral became alarmed at the “many fatal effects” and ordered the rum cut with water. Disgruntled, the sailors dubbed the diluted drink “grog” and it became standard throughout the Royal Navy.

Source: Marine Corps Book of Lists