Complex sentence: Phipps and the "Ariel" captured the American privateer "New Broom" on 22 October 1778, and in February 1779 Captain Thomas Mackenzie took over command of the "Ariel".
Split into simpler sentences: Phipps and the "Ariel" captured the American privateer "New Broom" on 22 October 1778. The next year, in February, Captain Thomas Mackenzie took over command of the "Ariel".