Complex sentence: She served during the French Revolutionary and Napoleonic Wars under several notable naval commanders and played a key role in the Battle of Copenhagen under Captain Edward Riou, when Riou commanded the frigate squadron during the attack.
Split into simpler sentences: She served during the French Revolutionary and Napoleonic Wars, under several notable naval commanders. She played a key role in the Battle of Copenhagen when she was Edward Riou's ship while Riou commanded the frigate squadron during the attack.