German advances during the opening phases of Operation Barbarossa from 22 June 1941 to 25 August 1941 – public domain image map by the History Department of the US Military Academy

(9) SOVIET-BULGARIAN WAR

And now we have the first of two wars that were effectively separate from the Nazi-Soviet war but connected to it.

Bulgaria was an Axis ally of Germany but was careful not to declare war against the Soviet Union and to remain as neutral as possible in Germany’s war with it, although Bulgaria was very much involved as a Germany ally against Greece and Yugoslavia.

I say as neutral as possible because the Bulgarian navy did participate in Axis convoys in the Black Sea as well as skirmishes with the Soviet Black Sea Fleet. Bulgaria also sent delegations of high-ranking officers, including the Chief of General of the Bulgarian Army, to German-occupied territory in the Soviet Union, as demonstration of its commitment to the alliance.

However, Bulgaria’s stance of official neutrality towards the Soviets did not save them from Soviet occupation or installation of a communist government, despite Bulgaria scrambling at the last moment to declare war against Germany. The Soviet Union declared war on Bulgaria, such that on 8 September 1944 Bulgaria “was simultaneously at war with four major belligerents of the war: Germany, Britain, the USA, and the USSR”.

Of course, of those four belligerents, only one counted – the Soviet Union, which invaded Bulgaria the following day without resistance by Bulgaria.

(10) HUNGARIAN-ROMANIAN WAR

The second of two wars effectively separate from the Nazi-Soviet war but connected to it – although the term war is overstating the hostility between them, which did not break out into actual war, at least while both were allies of Germany. Cold war might be a better term.

There was a Hungarian-Romanian war but it was in the immediate aftermath of the First World War, from 13 November 1918 to 3 August 1919. Not surprisingly, Romania won, given that Hungary was one part of the dual monarchy of the Austro-Hungarian Empire that had gone down to catastrophic defeat by the Allies.

During the First World War however, it had been Romania that had gone down to catastrophic defeat on the Allied side, although it had a reversal of fortune from the final Allied victory.

That saw Romania gain the longstanding source of hostility between it and Hungary – Transylvania, which had a majority Romanian population but which had been controlled by Hungary, either as a kingdom of itself or as part of the Austro-Hungarian Empire.

Another Hungarian-Romanian war loomed as Hungary sought to reclaim Transylvania, but Germany “arbitrated” the cession by Romania to Hungary of Northern Transylvania in August 1940 – obviously favoring Hungary as an ally as opposed to a Romania that was still nominally a British ally by Britain’s military guarantee to Romania (in much the same terms as its guarantee to Poland).

Romania became a German Axis ally under the new fascist government of Antonescu on 23 November 1940 but remained hostile to Hungary, such that Romanian troops in the Soviet Union could not be stationed alongside their Hungarian counterparts for fear of them fighting each other.

Romania under Antonescu apparently considered a war with Hungary over Transylvania an inevitability after German victory over the Soviet Union. As it was, Romania got its war with Hungary as well as Northern Transylvania back – not under Antonescu or as a German ally but on the Allied side fighting alongside the Soviets against the Germans and Hungarians from September 1944.