Complex sentence: Coast Guard Squadron One was a combat unit formed by the United States Coast Guard in 1965 under the operational control of the United States Navy during the Vietnam War and assigned duties in Operation Market Time.
Split into simpler sentences: Coast Guard Squadron One was a combat unit formed by the United States Coast Guard in 1965 for service during the Vietnam War. Placed under the operational control of the United States Navy, it was assigned duties in Operation Market Time.