Complex sentence: He was educated in Zagreb where he left school in order to pursue a career as a military veterinarian, but he could not stand military discipline, so in 1894 he deserted the Austro-Hungarian Army and found shelter in Serbia.
Split into simpler sentences: He was educated in Zagreb where he left the school in order to pursue career of military veterinarian. He couldn't stand military discipline so in 1894 he deserted from Austro-Hungarian Army and found shelter in Serbia.