Derek Proudmoore was the first son of Grand Admiral Daelin Proudmoore, and elder sibling of Tandred and Jaina. Being the eldest son, Derek was first in line to inherit the Merchant-Kingdom of Kul Tiras. ( )
During the Second War, Derek was in command of a destroyer in the Third Fleet, accompanying his father in battle against the orcish navy. Without warning, they came under attack by dragon riders in the service of the Horde. Though he attempted to warn his father of the danger, Derek was incinerated by one of the dragons as he stood on top of the crow's nest. His boat was sent to the bottom shortly thereafter.
Kurdran Wildhammer and his gryphon riders joined the battle shortly afterward, killing several dragon riders while their gryphons helped slaughter the dragons. The remaining dragon riders fled and were pursued by Kurdran and his brethren, allowing Admiral Proudmoore to focus on destroying the orcish navy, ensuring his son's death wasn't in vain.