In 1961, Gomes, acting as under-secretary of state for the Army, was involved in a constitutional "coup d'état" headed by the Minister of Defense, General Júlio Botelho Moniz, that tried to convince President Américo Tomás to remove an aged António de Oliveira Salazar from the premiership.

On 12 September 1972 Gomes was called back to Portugal to occupy the post of Chief of the Armed Forces—replacing General Venâncio Augusto Deslandes [pt]—but he was replaced in March 1974 for refusing to swear his loyalty to the President of the Council of Ministers Marcelo Caetano in a public ceremony.

After the Carnation Revolution in 25 April, Gomes was one of the seven military leaders who made up the National Salvation Junta.

Following Spinola's resignation on 30 September 1974, Gomes was named as the President of the Republic by the reorganised Junta and served until 13 July 1976, when he was succeeded by General António Ramalho Eanes, who won the 1976 Portugese presidential election.

Gomes died of respiratory failure at the age of 87 at the Lisbon Military Hospital on 31 July 2001.