Ahh, yess... The Spanish Civil War, where German technology was light years ahead of the rest, and where He111s outran all enemy fighters that the nationalists could throw at them.
Yes, sure, bring the SCW to AH... Let folks sit in biplanes barely doing 150 while watching the "uber" 109A/B/C/Ds and the He111B/C/D/Es totally dominate everything else.
Ah, no.
Actually the I-16s more than held their own compared to the 109. And where the biplanes were concerned the Germans had the worst fighter by far in the He-51. The SB2 was doing its thing before the He-111 or Do-17, outrunning the Condor Legion and the Nationalists, when the Ju-52 was among the "Uber" nationalist bombers along with the S.M.81.
In the early years of the war the technology decidedly favored the Republicans (in the air), though training and organization was sorely lacking. In the latter years (particularly the last) the edge shifted, but that was more due to support and commitment, which had evaporated to a great degree internationally on the Republican side, as much as anything.
On the ground, just about anybody who could sell marginal junk in obsolete calibers made a killing at the Republican's expense.
Charon