Military attaché
Seregni joined the Army of Uruguay in 1931, and was promoted the junior officer rank of Alférez three years later. He rose to the rank of Colonel in 1958 and to General in 1963. In 1959 Seregni organized the evacuation of Paso de los Toros when the city was flooded in the Uruguayan floods of April 1959. He served as Military attaché to the Uruguayan Embassies in Mexico and the United States of America.