To find the country that suffered the fewest military and civilian deaths during World War II, we can look at the "Total Deaths" column of the table and compare the numbers for each country. Here are the total deaths for each country:
1. Germany: 4,280,000
2. Great Britain: 357,000
3. Japan: 1,972,000
4. Poland: 5,800,000
5. United States: 298,131
6. Soviet Union: 18,000,000
Among these numbers, the smallest value is 298,131, which belongs to the United States.
Thus, the country that suffered the fewest military and civilian deaths during World War II is the United States.