Vichy is a city in the central French department of Allier department. Located on the Allier river, it is a major spa and resort town and durin…Vichy is a city in the central French department of Allier department. Located on the Allier river, it is a major spa and resort town and during World War II was the capital of Vichy France. As of 2021, Vichy has a population of 25,789.