>>718922361
They kept units segregated by ethnicity. There's a good reason why Czechs mass revolted against the Austrians.
The only truly mixed one was the navy, where a single ship had ethnically diverse crew. But even then, different ethnics were given different roles in accordance to their traditions and specialty. (Croats and Italians made up the majority of sailors, but Czechs and Germans manned the main guns, whereas Hungarians would man the secondary guns and fill the role of weapon officer.)