 During the decade of 1940 Almirante Brown also acquired a land to build its headquarters in San Justo.In 1956 the club affiliated to Argentine Football Association filling the vacant left by defunct Deportivo San Justo, merged to Almirante Brown.In 1956 Almirante made its debut at "Tercera de Ascenso", the fourth division of the league system (current Primera D), winning its first official title that same season.