This is a map of present-day Poland, but this is not what independent Poland looked like between 1918--Poland was a part of the Russian Empire before 1918--and 1939, nor reflective of what happened to Poland during World War II when the country was partitioned by Nazi Germany and Soviet Russia.  As a result of agreements reached between Stalin, Churchill and Roosevelt near the end of the war, Poland was moved westward about 100 or so miles, meaning that parts of formerly eastern Poland were incorporated into parts of Belarus and Russia, and parts of formerly eastern Germany became now western Poland.