From The Fortress: The Siege of Przemysl and the Making of Europe’s Bloodlands, by Alexander Watson (Basic Books, 2020), Kindle pp. 247-248:
An officer’s existence in captivity, although psychologically straining, was generally not physically arduous. The Hague Convention of 1907, the international treaty governing the laws and customs of war on land, to which both Russia and Austria-Hungary were signatories, dictated that officers could not be forced to work and guaranteed them a regular salary. Generals received 125 rubles per month. Regimental officers were paid an entirely adequate 50 rubles. Especially in 1915 and 1916, living conditions were fairly comfortable. Some officers were permitted to live in houses. In the prisoner-of-war camps, they could afford extra furnishings and had soldier-servants. Sports and educational activities were organized. The Berezovka camp in Siberia became famous for its “extraordinarily rich” library, which was well stocked thanks to “officers from Przemyśl who brought with them a major part of the Fortress’s library.” Not only post but also telegraphic services were accessible. For Gayczak, this easily compensated for all the other hardship. At long last, after eight months of aching worry, he was able to contact his family in Russian-occupied Lwów. On April 19, 1915, he received a five-word telegram from his wife that left him euphoric with relief: “Everyone alive and healthy, Lucy.”
The fate of Przemyśl’s other ranks was far grimmer. For them the war was by no means over. The Russian army took 2.1 million Habsburg prisoners during the First World War. Horrifyingly, one in every five—around 470,000 men—died during their captivity.