Complex sentence: The Japanese knew of Corregidor's powerful 16-inch seacoast guns so they avoided a direct invasion on Manila by passing through Manila Bay, instead, they landed on parts of Northern Luzon, and slowly made their way down south, towards Manila.
Split into simpler sentences: The Japanese knew of Corregidor's powerful 16-inch seacoast guns so they avoided a direct invasion on Manila by passing through Manila Bay. Instead, they landed on parts of Northern Luzon and slowly made their way south towards Manila.