Complex sentence: Not only did North Vietnam conquer South Vietnam but the communist were also victories in Cambodia when the Khmer Rouge captured Phnom Penh on April 13 and so where the Pathet Lao successful in capturing Vientiane on December 2.
Split into simpler sentences: Not only did North Vietnam conquer South Vietnam but the communist were also victories in Cambodia when the Khmer Rouge captured Phnom Penh on April 13. As where the Pathet Lao successful in capturing Vientiane on December 2.