The 20th-century Argentine leader referred to in this crossword is Juan Perón, who served as President of Argentina from 1946 to 1955 and again from 1973 to 1974. He was a major figure in Argentine politics during the mid-20th century, and his policies had a lasting impact on the country. He was known for his populist approach to politics, and his wife, Eva Perón, was a powerful political figure in her own right.