Simplify the following text for a Grade 13 native English-speaking person.
Original: In September 1943 , with the Italian collapse and the surrender of Italian fleet , naval actions in Mediterranean became restricted to actions against U-boats and by small craft in the Adriatic and Aegean seas .
Simplified: In Sept 1943 with the Italian collapse and the surrender of Italian fleet , naval actions in Mediterranean became restricted to actions against U-boats and by small craft in the Adriatic and Aegean seas .