Complex sentence: The attention of the Allies then switched back to the central east coast, with Oboe 2, the last major amphibious assault of World War II, at Balikpapan on 1 July 1945.
Split into simpler sentences: The attention of the Allies then switched back to the central east coast, with Oboe 2. The last major amphibious assault of World War II was at Balikpapan on 1 July 1945.