Complex sentence: He was the helmsman on the USS "Enterprise"-E during a Borg incursion and while on a mission outside the ship, Hawk was assimilated by the Borg and subsequently killed by Worf.
Split into simpler sentences: He was the helmsman on the USS "Enterprise"-E during a Borg incursion. While on a mission outside the ship, Hawk was assimilated by the Borg and subsequently killed by Worf.