Essential reading ...
Tom Wintringham was a captain with, and eventual commander of, the British Battalion of the International Brigades.
This memoir describes the battle of Jarama (in which he fought and was wounded) in a lot of detail. It also contains information on the war in general, and reflections on tank warfare including detail on how to knock one out with a petrol bomb.
Chauchat and petrol bomb
Chauchat LMG - figure from Northstar. The International Brigade were issued with these at Jarama and complained heavily about their unreliability. Petrol bomber is a Black Tree partisan. Tom Wintringham recommends using 2lb jam jars for petrol bombs but all available figures seem to have bottles.
Officer and medic
Officer has British equipment (he is in fact a Footsore figure aimed at VBCW). This is realistic for the Madrid front where this seems to have been common. Robert Capa took several pictures of Lee Enfield armed republicans and they appear in the Nationalist list of equipment siezed at the Ebro. Apparently the Russians supplied a lot of equipment captured following the Arkangelsk expedition.
Medic is Dixon.
Autocannon
Two Oerlikon/SEMAG autocannon. These were supplied by Mexico. They are basically an anti-aircraft gun mounted on a different carriage and used as a heavy machine gun.
Guns are Empress, from their Interwar range, with the wheels and crew swapped.
IB rank and file
A whole crowd of International Brigadiers. Figures are a right mixture, but there are a lot of Northstar and Empress among them.
Maxim
Copplestone figures from their Russian Civil War range withe head swaps, apart from the pointing chap who is Templar.
And another Maxim
Warlord figures, apart from the standing one which is Templar.
LMGs and mortar
LMG teams from Empress and Templar. Mortar is Empress.