Complex sentence: Realizing that civil war was now increasingly probable, Nakaoka returned to Tosa and established the "Rikuentai" militia, modeled after the "Kiheitai" in Chōshū in July.
Split into simpler sentences: Realizing that civil war was now increasingly probable, Nakaoka returned to Tosa and established the "Rikuentai" militia. Rikuentai was modeled after the "Kiheitai" in Chōshū in July.