Complex sentence: After defeating the Titan Krios at the Battle of Mount Othrys, ("happened at the same time as the Titan war of Olympus") It's also mentioned by Aelous that Jason defeated the giant sea monster from the Trojan war.
Split into simpler sentences: After defeating the Titan Krios at the Battle of Mount Othrys, (whis is said to have happened at the same time as the Titan war of Olympus). It is also mentioned by Aelous that Jason defeated the giant sea monster from the Trojan war.