Complex sentence: Saumarez sent messages in the frigate HMS "Thames" recalling Keats, who followed Saumarez towards Algeciras, and was in sight of the admiral's ship on the horizon at dawn on 6 July.
Split into simpler sentences: Saumarez sent messages in the frigate HMS "Thames" recalling Keats. Keats followed Saumarez, and was in sight on the horizon from the admiral's ship at dawn on 6 July.