Explanation:
United States military operations in other countries are numerous and its military power is gigantic they are capable to remove themselves from the occupied countries.
These US presidents were in power in the times right before the start of the Civil War (1861-1865)
Martin Van Buren (1782-1862) was the 8th President of the United States from 1837 to 1841. He had to face the important economic recession that took place in 1837. In 1840 a federal central bank for the US was created.
William Henry Harrison (1774-1841) was the 9th President of the United States, who entered in office in 1841, and died that same year. His presidency was extremely short. His death triggered a constitutional crisis.
John Tyler ( 1790-1862) was the 10th President of the United States from 1841 to 1845.
James K. Polk (1795- 1849) was the 11th President of the United States from 1845 to 1849.
