William Worth Belknap's argument was simple, if not a model defense: you can't impeach someone who is no longer in office.
Born in Newburgh, New York in 1829, Belknap graduated from Princeton University in 1848, studied law at Georgetown University, and was admitted to the bar in 1851. He moved to Iowa, briefly entering government work in 1857 when he was elected as a Democrat to one term in the state legislature.
When the Civil War broke out in 1861, Belknap joined the Union Army and became a major in the 15th Iowa Infantry. He fought at Shiloh, Corinth, and Vicksburg before taking part in the campaign from Chattanooga to Atlanta. In 1864, he was promoted to brigadier general and given command of the 4th division of the XVII Corps. Belknap joined General William Sherman's march through Georgia and the Carolinas. When he was mustered out in 1865, Belknap was a major general; he had also switched parties to join the Republicans.
After the war, Belknap returned to Iowa and served as a collector of internal revenue from 1865 to 1869. In that year, President Ulysses S. Grant appointed him to be Secretary of War after the death of John A. Rawlins. In a time of relative peace for the country, Belknap's activities in this position included starting preparation of historical reports by post commanders, advocating preservation for Yellowstone Park, launching a secretarial portrait gallery, and recommending that Congress fix May 1 as the start of the fiscal year. He was evidently not supportive of the Freedmen's Bureau.
Belknap's annual salary was $8,000, though he was known for living in a certain amount of luxury and throwing extravagant parties. The New York Times later reported that many acts of government corruption were considered unsubstantiated or invented, and investigations of wrongdoing were conducted "in an aimless, drifting manner." However, Belknap soon found himself fully exposed after the damning testimony in late February of 1876 by one Caleb P. Marsh of New York.
Marsh testified before the House Committee on Expenditures in the Department of War that Belknap's second wife, Carrie, encouraged him to apply for a post trader position at Fort Sill in Indian Territory. She asked for $6,000 a year to help convince her husband to appoint Marsh, though she also warned that Belknap had threatened to throw a man who offered $10,000 for a post trader appointment down the stairs. Such a position could be quite lucrative, with the New York Tribune reporting that a $15,000 investment could yield a $40,000 annual income. Not surprisingly, the current trader, John S. Evans, wasn't inclined to part with it.
Though Belknap was later charged with appointing Marsh to the position, Marsh never took the job. Instead, apparently with Belknap's consent, Evans and Marsh entered into a contract which would allow Evans to keep his job; he agreed to pay Marsh $12,000 each year, half of which he was to pay to Carrie. The amount was subject to a proportional decrease if the number of troops at the fort fell below 100. The first payment rolled out in the fall of 1870.
Carrie died of tuberculosis in 1870. Marsh kept sending the payments to Carrie's sister, Amanda, ostensibly to help support Carrie's infant child. Belknap, if he didn't know about the arrangement from the start, received some of the payments while Amanda was traveling. The child died in 1871; Belknap later married Amanda, and the payments kept coming. According to the articles of impeachment later handed down in Congress, Belknap received $24,450 between 1870 and 1876.
Following Marsh's testimony, things moved with surprising speed. On March 1, 1876, Belknap apeared before the committee. They offered to hear him the next afternoon, but he didn't show up. Instead, on the morning of March 2, Belknap handed in his resignation to Grant. The President accepted, appointing the Secretary of the Navy to replace him. Within a week, he had appointed attorney Alphonso Taft to the post.
The House of Representatives immediately took up the question of whether it had the authority to impeach Belknap, since impeachment cannot impose fines or imprisonment but only remove someone from office or disqualify them from holding office. Hiester Clymer, Democrat of Pennsylvania and chairman of the Committee on Expenditures in the War Department, described Belknap as "the proper outgrowth, the true exponent, of the corruption, the extravagance, the misgovernment that have cursed this land for years past." The House unanimously voted to have the Senate go ahead with the impeachment process.
As the impeachment process moved along, Marsh fled to Canada. Congressman Lucius Q.C. Lamar, a Democrat of Mississippi, said that Marsh's flight took with him any chance of a criminal indictment of Belknap. "Now, gentlemen, we have all the proceedings which have been been taken in this House and all the testimony which has been brought before it against William W. Belknap," said Lamar. "But with Marsh absent it is useless, and there is no way of criminally proceeding against William W. Belknap." A grand jury still managed to find enough to indict Belknap on bribery charges in May. The Times had reported prior to the indictment that he faced up to three years in prison and a fine three times the amount taken if convicted.
The Senate took up five articles of impeachment against Belknap, which included one colorful charge that he had been "basely prostituting his high office to his lust for private gain." When he was tried before the senators, he repeated the argument that the impeachment did not apply to him, since he was no longer a United States officer but simply a citizen of Iowa. The official Senate reply stated that his argument did not hold water, since the malfeasance occurred during his time as Secretary of War.
After over 40 witnesses came before the Senate, 35 senators voted that Belknap was guilty; 25 voted that he was not guilty, although 23 of them said that it was only because they felt that Congress did not have jurisdiction in the matter. The Times dubbed the whole impeachment affair "a rather stupid and uninteresting farce," and said that it set a precedent in allowing any civil officer to "escape the penalty fixed by the Constitution by hastening to resign as soon as his deeds are disclosed." The newspaper noted how the criminal indictment still stood, but guessed that it would not hold up in light of the "rather common robbers" involved in a $47,000 theft from the Treasury managing to avoid prosecution. The writers were prophetic in this matter, as the charges against Belknap were dismissed in February of 1877 for lack of evidence.
Belknap returned to practicing law, moving first to Philadelphia and then back to Washington. He died in 1890 of an apparent heart condition.
Sources: The Biographical Directory of the United States Congress, The Senate Historical Office, Secretaries of War and Secretaries of the Army by William Gardner Bell, "The New Secretary of War" in the New York Times on Oct. 14 1869, "Gen. Belknap's Career" in the New York Times on Mar. 3 1876, "The Case in the House" in the New York Times on Mar. 3 1876, "The Testimony" in the New York Times on Mar. 3 1876, "The Event at the Capital" in the New York Times on Mar. 3 1876, "The Belknap Impeachment" in the New York Times on Mar. 31 1876, "Belknap Indicted" in the New York Times on May 4 1876, "Acquittal of Belknap" in the New York Times on Aug. 2 1876, "The Suit Against Gen. Belknap" in the New York Times on Feb. 9 1877, "Belknap's Sudden Death" in the New York Times on Oct. 14 1890, Grant: A Biography by William S. McFeely, Lucius Q.C. Lamar: His Life, Times, and Speeches 1825-1893 by Edward Mayes, Appleton's Annual Cyclopaedia and Register of Important Events of the Year 1876