Why was Johnson put through the impeachment process? Did it work?

Technically, Andrew Johnson was impeached for violating the Tenure of Office Act, a measure passed by congressional Republicans that forced the President to consult the Senate before firing Cabinet officials. Johnson removed his political rival, Secretary of War Edwin Stanton from office in defiance of this law, and was duly impeached by Radical Republicans in the House of Representatives. As with most struggles between the President and Congress, the motives for impeachment went deeper. Johnson had consistently opposed the Reconstruction measures of House Republicans, vetoing the Civil Rights Act of 1866 as well as the Freedmen's Bureau, both of which were intended to protect the rights of black men and women in the South. So impeachment was a political move. Whether it "worked" or not largely depends on an understanding of how impeachment works. "Impeachment" is often used in popular discourse to mean the removal of the President. But in reality, impeachment is only the act of bringing charges against the President. This must be done by a majority of the House, as it was (by a very large majority) against Johnson. However, only the Senate, essentially acting as a jury, may actually remove a President, which can only be done by a two-thirds vote. After a very long deliberation, the Senate fell one vote short of the two-thirds vote needed for removal, so efforts to remove Johnson were not successful. But the very act of bringing charges against Johnson weakened the President, and he was able to stay in office only because he agreed in principle not to oppose the Reconstruction initiatives of his Radical Republican rivals. So the impeachment of Johnson ended up being a successful political gambit on their part.