After graduating from the Argentine military college in 1904 as a second lieutenant, Ramírez was promoted in 1910 as first lieutenant of the cavalry. In 1911, he was sent to Germany for training with the Fifth Hussars cavalry in Kaiser Wilhelm's Prussian Army. He returned home in 1913, with a German wife, prior to the outbreak of World War I. Advancing in rank as a specialist in cavalry tactics, he assisted fellow General José Félix Uriburu in a authoritarian coup that deposed Hipólito Yrigoyen in 1930. Ramírez was sent to Rome to observe Mussolini's army until his return in 1932.

When Uriburu set free elections and died, General Ramírez worked behind the scenes to plan a return of fascism to Argentina. Over the next several years, he organized the Milicia Nacionalista (later the Guardia), and authored a program for a state ruled by the militia. In 1942, Ramírez was appointed as War Minister by President Ramón Castillo, and began to reorganize the Argentine Army. At the same time, the Guardia Nacional joined with another party to form "Recuperacion Nacional," a fascist political party. Castillo fired Ramírez following a cabinet meeting on May 18, 1943. Two weeks later, on June 4, 1943, Ramírez assisted Arturo Rawson in overthrowing Castillo's government, and was again made Minister of War. Three days later, on June 7 Ramírez forced Rawson's resignation and maintained Argentina's neutrality during World War II. Argentina was torn by then between Britain, who wanted the country to stay neutral[citation needed], and the U.S., who wanted it to join the Allies. Ramírez stayed neutral and, consequently, the United States refused requests for Lend-Lease aid. Argentina finally declared war on Germany and Japan during the government of Edelmiro Farrell.

Despite having been brought to power through a coup d'état, Peronist historiography never calls him a dictator.