Charles Borromeo was the Archbishop of Milan from 1564 to 1584 and a cardinal of the Catholic Church. He was a leading figure of the Counter-Reformation combat against the Protestant Reformation together with Ignatius of Loyola and Philip Neri. In that role he was responsible for significant reforms in the Catholic Church, including the founding of seminaries for the education of priests. He is honoured as a saint by the Catholic Church, with a feast day on 4 November.

Pope Pius IV, born Giovanni Angelo Medici, was head of the Catholic Church and ruler of the Papal States from 25 December 1559 to his death, in December 1565. Born in Milan, his family considered itself a branch of the House of Medici and used the same coat of arms. Although modern historians have found no proof of this connection, the Medici of Florence recognized the claims of the Medici of Milan in the early 16th century.