On October 20, 1387 all heads of families were invited on the square of the oven to solemnly swear allegiance to the House of Orleans, as the village had been brought as a dowry by Valentina Visconti to Louis de Beaumont, Duke of Orleans, son of the King of France Charles V. In 1414 Portacomaro was attacked and plundered by mercenaries and destroyed; the population took refuge in Asti, and returned with soldiers to reconquer their village.
In the Gallery of Maps at the Vatican Museums is a fresco of "Pedemontium et Monsferratus", where the name "P.Come" appears and the village is portrayed as fortified by walls with a central arched doorway with two towers to its side, houses and three towers. In the 16th century the Coardi Counts, ancient family of Spanish origin, were lords of Portacomaro; then the place passed to Count G.B.Bogino, a minister of the House of Savoy.
In 1837, by decision of Carlo Alberto, King of Sardinia, Portacomaro merged with the municipality of Migliandolo. A period of prosperity followed with the cultivation of vineyards, and roads and a railway made communications easier.