Complex sentence: Franco's ultranationalist faction received military support from several fascist groups, especially Nazi Germany and the Kingdom of Italy, while the Republican side was supported by Spanish communists and anarchists as well as help from the Soviet Union, Mexico, and the International Brigades.
Split into simpler sentences: Franco's ultranationalist faction received military support from several fascist groups, especially Nazi Germany and the Kingdom of Italy, while the Republican side was supported by Spanish communists and anarchists. It also received help from the Soviet Union, Mexico, and the International Brigades.