Complex sentence: In order to appease the restless Poles, the Austrian authorities gave in to many of their demands which included greater Polish control over lands at the expense of the Ukrainian rivals who had delared their loyalty to Austria.
Split into simpler sentences: In order to appease the restless Poles, the Austrian authorities gave in to many of their demands. The demands included greater Polish control over lands at the expense of the Ukrainian rivals, who had declared their loyalty to Austria.