Complex sentence: In the battle, the Spanish lost over 65% of their men; the survivors took refuge in the castle of Puerto Cabello, which, until it was taken by Páez and his men in 1823, was the last Spanish stronghold in Venezuela territory.
Split into simpler sentences: In the battle, the Spanish lost over 65% of their men; the survivors took refuge in the castle of Puerto Cabello. Until it was taken by Páez and his men in 1823, this was the last Spanish stronghold in Venezuela territory.