Defining the Pacific War or Taiheiyō Sensō, The second Sino-Japanese war, WW2 Pacific Theater, Dai Tō-A Sensō or “The Greater East Asia War”, 5. Jūgonen Sensō or “Fifteen Years’ War”, Zhōngguó Kàngrì Zhànzhēng or “The War of Resistance" and Chinese People’s War of Resistance against Japanese Aggression to name just a few titles!. When did the Pacific War start and how does it fit into World War Two overall? History Matters.