Complex sentence: Early in October, she participated in exercises with Transport Division 6; then, on Friday, 13 October, headed for Humboldt Bay, the staging area for the impending invasion of Leyte.
Split into simpler sentences: Early in October, she participated in exercises with Transport Division 6. Then, on Friday, 13 October, she headed for Humboldt Bay, the staging area for the impending invasion of Leyte.