Complex sentence: An energetic and resourceful man, he was a cavalry officer in Austro-Hungarian army in the First World War, was captured by the Russians, interned in a camp near the Korean border and escaped across Siberia with the help of Catholic priests.
Split into simpler sentences: An energetic and resourceful man, he was a cavalry officer in Austro-Hungarian army in the First World War but was captured by the Russians. He was interned in a camp near the Korean border but escaped across Siberia with the help of Catholic priests.