Complex sentence: In a separate incident later that night, British forces engaged an Argentine patrol gunboat, the ARA "Alferez Sobral", that was searching for the crew of the Argentine Air Force Canberra light bomber shot down on 1 May.
Split into simpler sentences: In a separate incident later that night, British forces engaged an Argentine patrol gunboat, the ARA "Alferez Sobral". At the time, "Alferez Sobral" was searching for the crew of the Argentine Air Force Canberra light bomber shot down on 1 May.