Complex sentence: The 7th and 15th Soviet Armies advancing behind collapsing White Russian forces continued to attack fortified positions at the Estonian border near Narva, first clashes took place on Luga River on 16 November, starting the conclusive battles with 120,000 Soviets facing 40,000 Estonians.
Split into simpler sentences: The 7th and 15th Soviet Armies advancing behind collapsing White Russian forces continued to attack the fortified positions at the state border near Narva. First clashes took place on Luga River on 16 November, starting the conclusive battles with 120,000 Soviets facing 40,000 Estonians.