Historical Abstracts is the best database to use when looking for academic journal articles in the field of modern European history for the period 1450 to the present.
Link your search terms using the AND connector. For example: spain and civil war and international brigades. On the search results screen, use the options on the left toolbar to narrow your search results. To find the fulltext of the article (if not provided directly in the database), click on the "Check for Full Text" button and work your way through the screens. Not all articles will be online, some may only be in print, others may not be available at the UW. Articles from journals which the UW does not own can be requested via Interlibrary loan.