ICPSR (Inter-university Consortium for Political and Social Research) is a major repository of political and social quantitative datasets.
Searching is free, but to download the dataset, one must be a member of American University.
One uses ICPSR if one needs a large set of data.
For example, I am looking for statistics on military conflicts in Africa since the end of World War II.
One way to find datasets in ICPSR is to search it. Keep your search terms simple. I am using just the word: military.
I could then limit my results by geography. In this case, I would limit it to Africa.
Two results look promising.
The codebook, that is, the text of the study, is free. To download the data, select the desired format and then log in. For first time users, there is a free registration. Once you have been approved, you can download the data anywhere so long as you are an AU student, faculty or staff.