In your lecture about the 1850s, you mentioned military filibusters being executed by a guy named Walker.
Where can I find out more about this?
Other than the Sectional Conflict debate (and ultimately the Civil War), were there any other long term impacts?
His name was William Walker. There are several secondary sources about his activities, some of which are in the public domain. The link below is his own work about Nicaragua. These events had little to no impact on the U.S. after the War.