On foreign and military policy, Lincoln spoke against the Mexican–American War, which he imputed to President James K. Polk's desire for 'military glory—that attractive rainbow, that rises in showers of blood.' He supported the Wilmot Proviso, a failed proposal to ban slavery in any U.S. territory won from Mexico.Lincoln emphasized his opposition to Polk by drafting and introducing his Spot Resolutions. His legal reputation gave rise to the nickname 'Honest Abe'.Lincoln argued in an 1858 criminal trial, defending William 'Duff' Armstrong, who was on trial for the murder of James Preston Metzker.