I recently learned about Division Azul (Blue Division), Spain’s contribution to the fight against Communism. Long story short, after Germany invaded the USSR, Spain sent a division of volunteers (initially, conscripts later) to the Eastern Front. Their uniforms featured blue shirts, hence the name, though they wore Wehrmacht uniforms outside Spain. Division Azul, which included a fighter squadron, was designated 250th Infantry Division by the Germans. The unit served with distinction against the Soviets, but was withdrawn by Spain when the tide of the war turned in 1943.
Not that the Germans need more help against the Russian bear, but I thought a house rule to inject a bit of historical flavor might be fun. Here’s my initial idea, though I’m open to suggestions:
During the non-combat move phase of the German turn in which they declare war on the USSR (or the first German turn following a Soviet DoW on Germany), one infantry unit may begin moving from Spain to the Eastern Front. Movement must be as direct as possible. When the infantry unit reaches any territory bordering an original Soviet territory, it is joined by one fighter. Both units are treated as annexed pro-Axis neutrals and immediately come under German control.
Spanish units may only engage in battle against Russian units. When any non-Soviet Allied powers capture or liberate a territory on the European continent (the area bordered by Denmark to the north, Normandy to the west and Greece to the south, not including islands in the Med), the Spanish units are immediately withdrawn from battle. The infantry unit is returned to Spain, while the fighter is removed from the board.