In June 1849, at age twenty, Knapp along with his uncle Charles wrote a letter to Abraham Lincoln, in support of Lincoln's efforts to secure himself a political job as the Commissioner of the General Land Office in Washington. Lincoln had written to Knapp's father two days earlier asking for support.
In June 1849, at age twenty, Knapp along with his uncle Charles wrote a letter to Abraham Lincoln, supporting Lincoln's quest for a political role as the Commissioner of the General Land Office in Washington. Lincoln had previously sought backing from Knapp's father.