A scenario taken from Mark Hannam's Rompan el Fuego! representing 'The Vizcaya Offensive', 31 March 1937 - a case of Roman Catholics vs Roman Catholics, as this was part of the Nationalist offensive into the Basque Country.
In the (nominally) Red corner:
(I should have made a Basque flag!)
Republicans representing the Guardis militiamen.
In the Blue corner:
Carlists, with artillery support, and:
Mixed Italian CTV and Blueshirts.
At this point, there was no air support from the Condor Legion, due to bad weather - so that solves that Portable problem.
VIVA CRISTO REY!
(That will be Christ the King who put away Peter's sword...)