Final answer:
The failure to remove U.S. Presidents in 1868 was due to the high threshold for conviction in the Senate, political dynamics post-Civil War, and concerns about the succession of Radical Republican Benjamin Wade if Andrew Johnson had been removed.
Step-by-step explanation:
The reasons why attempts to remove U.S. Presidents resulted in failure in 1868 revolve primarily around political dynamics and legal thresholds for conviction. President Andrew Johnson, who faced impeachment after the Civil War, avoided removal by a single senator's vote. The impeachment process itself is deliberately difficult, requiring a supermajority in the Senate to convict and remove a president from office. Johnson's impeachment was largely due to policy disagreements with Congress on the Reconstruction of the South.
Further complicating matters, the political environment of the time was characterized by strife and divided interests post-Civil War. The Tenure of Office Act of 1867, intended to restrict Johnson's powers, triggered his impeachment when he removed the Secretary of War, Edwin Stanton, from office. Johnson's actions were seen by many as a violation of this act. However, the impeachment proceedings were inherently political, with moderate Republicans joining Democrats in acquitting Johnson, fearing the accession of Radical Republican Benjamin Wade to the presidency.
These events occurred in the backdrop of a nation still healing from civil conflict, with Northerners growing tired of the focus on the South and white Southerners resisting federal control, all of which prejudiced public and political appetite for decisive actions against the president.