Question

Although there were fewer than 200 soldiers in Pizarro's group, they defeated an empire of about 12,000,000.

Is the dependent clause adjectival or adverbial.
Writeacher
Adjective clauses start with these words: which, who, whose, whom, that.
http://web2.uvcs.uvic.ca/elc/studyzone/410/grammar/adj.htm

Adverb clauses start with any of a whole raft of subordinating conjunctions:
http://web2.uvcs.uvic.ca/elc/studyzone/410/grammar/advcls.htm