The Spanish Civil War - pg. 211

Servicio de Investigacion Militar was later described
as 'the Russian syphilis' by the German writer, Gustav Regler,
who served in the International Brigades. This particular variety
of the disease can, of course, be ascribed to Russian carriers, but
one cannnot say that, if Orlov and his NKVD men had not come to
Spain, nothing of the sort would have happened. If Russian
communism appeared to its critics as Tsarism with a proletarian face,
then Spanish communism, with its power base in New Castile, seemed
to them to be growing into a Marxist variation of Phili II's integrated
state based on the army. The SIM resembled the Inquisition and
the commissars the church.