On The Road to the Alto Douro - Part One
Port wine became popular in England in the late 17th century, when British merchants who settled here began to add brandy to the wine of the Douro valley to prevent it from souring during transit.
They discovered that the sweeter and stronger the wine, the better the taste. In 1703 Britain and Portugal signed a treaty providing for the exchange of cloth from England for barrels of Portuguese wine.
This paved the way for the enormous expansion in the 18th-19th centuries of the Port trade.
72 Hours in Porto