Complex sentence: The Jesuits finally returned to Basilan and Tetuan on 1862, and by 1879, the Spanish garrison built a "floating" Naval Hospital on shallows guarding the eastern entrance to the Isabela Channel.
Split into simpler sentences: The Jesuits finally returned to Basilan and Tetuan on 1862. And in 1879, the Spanish garrison built a "floating" Naval Hospital on shallows guarding the eastern entrance to the Isabela Channel.