Which US president served a single term, was a former military general, and was often associated with the Whig party despite having been elected as an independent?

1. His presidency was marked by a high level of political infighting and disagreement.
2. He was a war hero before becoming president but his time in office is considered by many to have been largely unremarkable.
3. He became president due to a political deadlock and unexpected circumstances.
4. His administration took place during a period of heightened national tension over slavery and westward expansion