The Portuguese military records are in the process of being digitzed and put online. Presently, the records only cover 1900--2000 but they are putting more on everyday so keep checking.
The site is in Portuguese, but can easily be translated using an online translator such as Google Translate. The following is some of the description from the main page, to give you an idea of what can be found here:
The Master or Matriculation books have the records of the Portuguese male population, from the 18th and 19th centuries, distributed in 3,822 books and enrolled in 420,000 sheets. The information contained in these master books is very rich, especially in the scope of History, Sociology, Anthropology and Genealogy. ….
With the realization of this project it is possible for the researcher or consultant to access the information that allows him, for example, to design his family tree from the information available, it is also possible to retrieve all the information about a particular military man about decorations, praises, punishments, promotions, campaigns ... This project is undoubtedly an asset for genealogy and military history, as well as for researchers and for the citizen in general.
Projeto GERMILGenealogia em registos militares