Vichy is a city in the Allier department in central France. Located on the Allier river, it is a major spa and resort town and during World War II …Vichy is a city in the Allier department in central France. 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.