Complex sentence: Juan eventually died in the battle of Sacsayhuamán, an Inca fortress near Cuzco, when he tried to break the siege of Cuzco by leading an army out of the palace and attacking the Inca fortress.
Split into simpler sentences: Juan eventually died in the battle of Sacsayhuamán, an Inca fortress near Cuzco. He was attempting to break the siege of Cuzco by leading an army out of the palace and attacking the Inca fortress.