Complex sentence: After he completed his military service, Gastaldon returned to Rome where his parents were living at the time and over the next four years he continued composing songs and short pieces of instrumental music and started work on his first opera, "Fatma".
Split into simpler sentences: After he completed his military service, Gastaldon returned to Rome where his parents were living at the time. Over the next four years he continued composing songs and short pieces of instrumental music and started work on his first opera, "Fatma".