Complex sentence: Among them Yugoslavs, Russians, Ukrainians, Dutch, Spaniards, Greeks, Poles, and even some Germans disillusioned by national socialism, as well as British and Americans, either ex-prisoners or advisors deployed by SOE, SAS and OSS.
Split into simpler sentences: Among them Yugoslavs, Russians, Ukrainians, Dutch, Spaniards, Greeks, Poles, as well as some Germans disillusioned by national socialism. And of course British and Americans, either ex-prisoners or advisors deployed by SOE, SAS and OSS.