The Caucasus Campaign in 1918 saw some truly bizarre events take place. There were a series of shifting, short lived and at times highly unusual alliances; at one stage the Germans were allied with the Georgians against the Ottoman Turks who were allied with the Armenians. At another time the Russian Bolsheviks fought an alliance of Armenians, Russian Socialists and Mensheviks who called themselves the Centro-Caspian Dictatorship for control of the city of Baku, and both of these groups fought the Germans, Georgians and the Turks.
Into this the British decided to step, sending an expedition from Southern Iraq, via Neutral (but extensively fought over) Persia to aid the Dictatorship against the Turks (and everyone else). To help them they enlisted the aid of a force of Red Army Cossacks who’d been stuck in central Persia since the money from Moscow had ceased the year before. They were commanded by a Major-General Lionel Dunsterville and this unusual group was called Dunsterforce. To get to Baku Dunsterville commandeered a ship in the Persian port of Enzeli called the President Kruger and resulted in what he later described as:
'A British General on the Caspian, the only sea unploughed before by British keels, on board a ship named after a South African President and whilom enemy, sailing from a Persian port, under the Serbian flag, to relieve from the Turks a body of Armenians in a revolutionary Russian town.' *
Now I’m not sure if that is the strangest military campaign ever but it is certainly the strangest I’ve ever heard of.
*From Eden to Armageddon: World War One in the Middle East by Roger Ford.