The Ganges River
Hope This Helps :P
Battle of Midway, because we destroyed most of the Japanese Navy, sinking four of their aircraft carriers along with lots of other ships. Japan would never recover from this, allowing the US to mostly dominate the Pacific with our Navy.
The Mediterranean Sea separated the Greek islands. These islands grew into separate city-states as they were separated by the sea.
The hills and mountains in Greece separated the individual city-states. These cities were separated by these hills and mountains, which led to them developing into different city-states.