"Mr. President, I thank you for the honor and privilege of serving you and the American people ... I am pleased to have been part of a team that launched the global war against terror, liberated the Afghan and Iraqi people, brought the attention of the world to the problem of proliferation, reaffirmed our alliances, adjusted to the post-Cold War world" and undertook initiatives to address poverty and disease in the Developing World, he said in the letter released by the White House Monday.
"I am especially honored to have led the dedicated men and women of the Department of State."
Powell's resignation letter indicated the possibility of his returning to private life was discussed with Bush in previous months. He submitted the letter Friday.
Powell, seen by many as the dove in an administration of Hawks, was one of four Cabinet secretaries whose resignations were announced Monday. The others were Energy Secretary Spencer Abraham, Agriculture Secretary Ann Veneman and Education Secretary Rod Paige.
The resignations of Attorney General John Ashcroft and Commerce Secretary Don Evans were announced last week.
Notable deaths of 2014 [PHOTOS]