For his performance in his career, with the entry of Brazil into World War I, he was appointed in October 1917 to attend the preparatory military mission which the Brazilian Army sent to France to fought the Western Front.

[4] That year, this regiment (as other French cavalry units) using Schneider and St Chamond models, at the cost of heavy losses, participated actively in the containment of German spring offensives, and later, already with the then new and revolutionary Renault FTs, in the successful final Allied counter-offensives.

He held the rank of captain, and was decorated by the Belgians and French, for courage in action, which he insisted should be credited to the bravery of his subordinates, who even came to gift him with grisly necklaces made with ears of enemy soldiers.

José Pessoa disagreed with most of those present, considering the discussion of existing laws or of new legislation to punish the crimes committed irrelevant, since the subject matter was the responsibility of jurists, not of the generals of the Army.

[15] Due to José Pessoas's opposition to military interference in politics, and to other frictions with the dominant current in power, the command of the army showed no interest in investing in development in order to apply also against possible external enemies, modern doctrine on the use of armor in warfare, since José was the main connoisseur and promoter in Brazil (who had recorded it in a book published in 1921 along with his experience in World War I), even when the country entered World War II.

[16] Being during this period, relegated to the minor functions in relation to this center, promoted to general-of-division in May 1940, traveled in 1943 to Paraguay like extraordinary ambassador to the possession of the president of that nation.

After going to the Reserve in September 1949, at the post of general-of-the-army (his promotion to marshal would occur only in January 1953), he continued to actively participate in the mobilization of public opinion in favor of a nationalist solution to the oil question, A participation that had begun in 1948, during the foundation of the Center for Studies and Defense of Oil and the National Economy (CEDPEN), together with Artur Bernardes and the generals Estêvão Leitão de Carvalho and Júlio Caetano Horta Barbosa.

[18] In 1954, he was invited by the then President Café Filho to serve as chairman of the New Federal Capital Location Commission, which was in charge of examining the general conditions of installation of the city to be built.

Next, Café Filho approved the choice of the site of the new capital and delimited the area of the future new Federal District, ordering the commission to conduct the study of all.