Complex sentence: In the autumn of 1937 Archduke Felix was permitted to return to Austria, entering the Theresian Military Academy in Wiener Neustadt he became the first Habsburg since the abolition of the monarchy to pursue a career as an officer in the Austrian Army.
Split into simpler sentences: In the autumn of 1937 Archduke Felix was permitted to return to Austria, entering the Theresian Military Academy in Wiener Neustadt. He became the first Habsburg since the abolition of the monarchy to pursue a career as an officer in the Austrian Army.