After that assignment and attending the Company Officers' Course and he was reassigned to Brooke General Hospital where he underwent his specialty training (residency) in internal medicine.

[2] In 1963, Méndez was assigned to medical research and development at Edgewood Arsenal in Maryland, where he served for less than a year and was once more sent to Fort Sam Houston.

In 1967, Méndez, who was then a lieutenant colonel, attended the Command General Staff College at Fort Leavenworth.

In 1972, he was selected to go to the Industrial College of the Armed Forces for a year and then he was reassigned to Fort Sam Houston, Texas, to the Academy of Health Sciences.

In 1975, he was assigned as the deputy chief of staff for operations of the Health Services Command and subsequently promoted to brigadier general.

[4] In 1983, Méndez was offered the position of Dean of the Ponce School of Medicine in Puerto Rico He accepted and moved to the island with his wife.

On December 5, 1989, President George H. Bush officially announced the nomination of Méndez for the position of Assistant Secretary of Defense for Health Affairs.

Among his responsibilities was to give health advice to the Secretary of Defense which at the time was Richard Bruce "Dick" Cheney.