He was educated in the capital, took the degree of civil engineer, and as such directed important works in Asturias and Galicia, entered the Cortes in 1856 as deputy for Vigo, and sat in all the parliaments until 1867 as member of the Unión Liberal with Marshal O'Donnell.
[1] On the proclamation of the republic Elduayen very earnestly co-operated in the Alphonsist conspiracy, and endeavoured to induce the military and politicians to work together.
He went abroad to meet and accompany the prince after the pronunciamiento of Marshal Campos, landed with him at Valencia, was made governor of Madrid, a marquis, grand cross of Charles III, and minister for the colonies in 1878.
[1] He accepted the portfolio of foreign affairs in the Cánovas cabinet from 1883 to 1885, and was made a life senator.
He always prided himself on having been one of the five members of the Cortes of 1870 who voted for Alfonso XII when that parliament elected Amadeus of Savoy.