General Benjamin M. Prentiss of Quincy, Illinois
Dr. David Costigan

When the Civil War erupted in April 1861, Benjamin M. Prentiss of Quincy (Adams County), a colonel in the Illinois militia, was given command of seven companies with which to defend Cairo, located at the critically important junction of the Mississippi and Ohio rivers. In late April his men seized munitions aboard river steamers bound for the South, an indication of his aggressiveness. It was done four days before the War Department authorized such confiscations. The Virginia-born Prentiss received some military experience as a militia lieutenant in Illinois’ Mormon “troubles” of 1844-1845 and as captain at the battle of Buena Vista during the Mexican-American War.

In August 1861 Prentiss received promotion to brigadier general, one of the early generalships awarded to Illinois. Most of those named were lawyer-politicians, with the exception of former U.S. Army captain Ulysses S. Grant. When Grant received an assignment to Cairo, he gave orders to Prentiss, who balked, claiming that he was the senior officer. Grant announced that by law, because of his former rank in the U.S. service, he was the superior officer. Prentiss demurred before leaving for St. Louis to seek another command. He subsequently was assigned to oversee northern Missouri above the Hannibal and St. Joseph Railroad. In his Memoirs, Grant lamented Prentiss’s decision to leave his command. He wrote: “General Prentiss made a great mistake…. When I came to know him better, I regretted it much…. He was a brave and very earnest soldier. No man in the service was more sincere in the cause for which we were battling; none more ready to make sacrifices or risk life on it.”

Dramatic events of April 1862 in western Tennessee vindicated Grant’s faith in Prentiss. The high point of Prentiss’s service came as he commanded the 6th Division of Grant’s Army of the Tennessee at the battle of Shiloh. Union troops encamped near Pittsburg Landing, Tennessee, were surprised by a rebel assault under the command of Gen. Albert Sidney Johnston. Prentiss’s troops managed to hold off the rebels for about six hours. Prentiss’s position was overrun and he was compelled to surrender. Nevertheless, some historians contend that Prentiss and his troops bought valuable time with their brave defense, which helped the Union forces on the second day turn the tables on the rebels at Shiloh, producing an important victory.

Prentiss remained in Confederate prisons until October 1862, when he was exchanged. He was rewarded for his service with a promotion to major general, reassigned to Grant’s command and detailed to oversee the defense of the eastern district of Arkansas.

In early July 1863, news arrived in Quincy that Prentiss’s troops had been attacked at Helena, Arkansas, by troops commanded by Confederate Gen. Sterling Price. The Quincy Daily Herald published Prentiss’s account of the battle. Prentiss had anticipated an attack and established formidable defenses, placing four batteries of artillery on heights overlooking invasion routes. Trees were felled to block roads. The outcome was an impressive victory. Prentiss’s forces were outnumbered by approximately 6,500 to 4,000. The victory, however, was overshadowed by the huge Union successes won at the same time at Gettysburg, Pennsylvania, and Vicksburg, Mississippi. The action at Helena, also ironically, constituted Prentiss’s final combat action. On July 17, less than two weeks after his notable victory, Prentiss returned to Quincy and was feted in a reception hosted by the activist women’s organization, the Needle Pickets. Prentiss sought a new command but none was forthcoming. In October 1863 he resigned from the army on grounds of health and family responsibilities. In fact, he was perturbed at being passed over for command. Gen. Stephen Hurlbut, a self-promoting officer and a fellow division commander at Shiloh, notified General-in-Chief Henry Wager Halleck that he disapproved of any position for Prentiss. Thus a “hero” of the battles of Shiloh and Helena spent the last eighteen months of the war at home.

The Prentiss story reveals more about Civil War leadership than immediately meets the eye. Early in the war the huge expansion of the military required a hurried search for leaders. Prentiss had served in the Mexican-American War and had run for political office, and thus appeared to fill the bill. He acquitted himself well at Cairo, Shiloh, and Helena, but authorities now decided that other officers better suited their plans for conducting the remainder of the war. The sorting process had consigned Prentiss to the sidelines.

Prentiss practiced law in his return to civilian life in Quincy. When Ulysses S. Grant became president in March 1869, he appointed his old comrade a federal pension agent. He served in this capacity for eight years. In 1881, Prentiss moved to Bethany, Missouri, where he served as general agent for the federal land office. In 1888, President Benjamin Harrison named him postmaster of Bethany and he was reappointed by President William McKinley. The government he had served had taken care of him with three separate patronage appointments. Prentiss died in 1901 at the age of 81.

Was Benjamin Mayberry Prentiss a politician who became a general? The answer must be a qualified one.

In the military situation brought on by the Civil War, there was need to almost instantly expand the army from about 16,000 troops to more than 75,000. Where were the officers to come from? Because of his previous military experience, Prentiss seemed a logical choice for command and acquitted himself quite well. Later in the war he was deemed of lesser competence and was deprived of additional commands. Whether this was a legitimate judgment is debatable. As a Republican politician he had advantages in receiving a significant command. His partisan posture likewise aided him in the postwar picture. Did the system work in Prentiss’s case? It can be concluded that a jerry-built structure worked tolerably well, and Prentiss brought credit to himself and to his community.

David Costigan is professor emeritus of history at Quincy University . He held the Aaron M. Pembleton Chair of History at Quincy University . He is a member of the advisory board of the Lincoln-Douglas Debate Interpretive Center.

Interested in learning more?
A sketch of Prentiss’s life can be found in Ezra J. Warner, Generals in Blue: Lives of the Union Commanders. Studies of the battle of Shiloh and role played in it by Prentiss and his division are: O. Edward Cunningham, Shiloh and the Western Campaign of 1862, Gary Joiner and Timothy B. Smith, editors; Wiley Sword, Shiloh: Bloody April; and James L. McDonough, Shiloh: In Hell before Night. Official eyewitness reports describing Prentiss’s action at Shiloh can be found in the Official Records of the War of the RebellionSeries I, volume 10, part 1, online at;cc=moawar;view=toc;subview=short;idno=waro0010.