Emperor Karl (Charles) I of Austria-Hungary inspecting troops of the newly formed Polish Auxiliary Corps (Polski Korpus Posiłkowy) in Bukovina, 10 December 1917. The officer on horseback is probably Lt. Col. Michał Rola-Żymierski, formerly commander of the 2nd Infantry Regiment of the Polish Legions.
The Corps was formed after Col. Józef Piłsudski, who started the Polish Legion from the pre-war Rifleman’s Association, in the summer of 1917 forbade Polish soldiers in the Austrian Army to swear a loyalty oath to the future (Austrian or German) king of Poland and the Central Powers but instead only to a planned independent Poland. The Germans arrested Piłsudski and locked him up in Magdeburg along with his followers while the men who still wanted to fight the Russians were enrolled in the new unit.
While the old Polish Legion numbered eight infantry and three cavalry regiments organized in three separate brigades, the “Corps” only numbered about 6,000 at its peak. In February 1918, when the Germans and Austrians gave large parts of ethnically Polish land to the new puppet Ukrainian government as a part of the carve-up of the old Russian Empire that was the Treaty of Brest-Litovsk, the Corps mutinied and about 1,500 made good as escape for White Russian lines while the remaining 5,000 ended up disarmed and in Austrian internment until that Empire, in turn, collapsed in November 1918.
As for Kaiser Karl, Hapsburg king for less than two years, he passed away in Portugal of pneumonia in 1922, aged 34. At the same time Karl took his last, Rola-Żymierski was serving as a general in the Polish Army while Piłsudski was the defacto head of the Polish state.