English, Scottish and Dutch wine traders, meanwhile, settled in north-western Portugal. After the River Lima silted up at Viana do Castelo, this foreign trading colony became concentrated around Porto (Oporto) and its twin city of Gaia across the Douro. The influence and power of these foreign traders increased hugely in the mid-17th century. Portugal needed England’s support against the Spanish, and conceded important privileges to the English merchants in a treaty of 1654.
In 1662 Charles II of England married Catherine of Bragança, sister of Alfonso VI of Portugal. Soon after, relations between England and France soured once again and then turned to war in 1689, and the English customs books of the time show a rapid switch from French to Portuguese wines.
In search of richer reds, the foreign merchants of Porto penetrated up-river, to the hot, isolated vineyards on the steep banks of the Douro beyond the Marão mountains. The rich but rustic Douro wines were fortified with brandy to keep them stable, and so Port was born.
At this time, Italian and Portuguese and later English wine trading families were also establishing businesses on the island of Madeira, much of their trade developing with the Americas.
The English have always been keen for a bargain where wine is concerned, and when a political deal at the turn of the millennium cut duty on Portuguese wine to a fraction of that on French wine, exports soared. The 1703 Treaty of Methuen between Portugal and England favored sales of English cloth in Portugal in exchange for this boost to sales of Portuguese wines.
The wines of Madeira were by this time beginning to be fortified and heat-aged on long sea voyages. Such was the demand for Port that the Douro wines are reported to have been ‘stretched’ with vinho verde-type reds, or high-acid, tannic reds from Bairrada. The wines of Lisbon, meanwhile, sold for higher prices, and were more highly prized. The tax advantage for Portuguese wines remained in place until 1860.
It was not until the mid-18th century that Portuguese wines began to be mapped and regulated. It was high time – the British were imperiously ruling the wine trade in Port country, malpractice was rife, quality on the descent, and wine exports likewise. There had been widespread planting, sometimes in unsuitable places, and various tricks were used to disguise the inadequacy of the wines (blending with wines from Spain, coloring with elderberry juice…).
To curb the influence of the British and support the Portuguese growers, strong-minded Portuguese first minister Sebastião José de Carvalho (later to be the Marquis of Pombal) introduced new laws, authorized specific vineyards for Port production, and had the elderberry trees ripped out! For the same reason, black cherry trees were ordered to be ripped out in Madeira. Meanwhile, in other parts of Portugal, he ordered vines to be uprooted from low-lying wetlands in favour of grain, which was in short supply, and was in any case a more appropriate crop for such land.