Carlos Martínez de Irujo y Tacón was first secretary of the Spanish Embassy in London, when he received a promotion and transfer as minister plenipotentiary of the Spanish legation in Philadelphia, replacing the chargé d'affaires, José Jáudenes y Nebot, who returned to Spain for a new assignment. Carlos Martínez de Irujo arrived in Philadelphia in the summer of 1796 and assumed his duties. Soon after arrival, the diplomat met, and apparently was captivated by, Sally McKean, the vivacious sixteen-year old daughter of Pennsylvania's chief justice and one of the state's most respected citizens—Thomas McKean. Two years later the couple married at St. Augustine Parochial Church in Philadelphia. Sally McKean, being from an influential American family, along with her own charm, grace, intelligence and beauty, contributed greatly to the success of her husband's mission in the United States. In 1802, as a result of his diplomatic services in Philadelphia, Martínez de Irujo received the Spanish aristocratic title of Marquis of Casa Irujo, with his Philadelphia-born wife becoming the first Marquise of Casa Irujo. He served as Spanish minister in Philadelphia and Washington, D.C., until 1808, when he was reassigned to Spain, accompanied by his wife and their six year old son. This Spanish diplomat culminated a brilliant professional career when he was named Secretary of State in 1819.