My mistake: there weren't 8,000 volunteers.
There were 9,640. Along with all the artillery, aircraft and AA-guns Sweden could spare. (which is, all of it, really)
"Finland's cause is ours!", indeed.

@DarkMage7280
Yeah, i learned about it in school and think most of the swedish came because if russia invaded Finland, Sweden would be the next.
Also, there was quite many estonians too in the wars.

From a *single* country.

I guess you are not right. During the Spanish civil war, the socialists organized more than 40.000 volunteers from many countries. See https://en.wikipedia.org/wiki/International_Brigades

@Joerg It should say from a SINGLE country :/