Let's come up with an amphibian race!

217th year. Kronn is killed by one of the rebels, but his son, Terenn, firmly holds the reins of power. 223rd year. Dark elves make their first attempt to descend underwater, but it fails. Development of new magic for underwater travel begins. 225th year. Terenn, fearing new raids by the elves, attempts to enter the dungeon.

Added 4 minutes later
By the way, we need to come up with a symbol for the faction. I suggest an octopus wrapping its tentacles around a ship. Or a statue of Neptune entwined with seaweed.