"[4] Following the election of Abraham Lincoln to the U.S. presidency in 1860 on a platform opposing the expansion of slavery into the territories, Benning took an active part in the state convention that voted to secede from the Union, representing Muscogee County.

[4] In a February 1861 speech to the Virginia secession convention, Benning gave his reasoning for the urging of secession from the Union, appealing to ethnic prejudices and pro-slavery sentiments to present his case and saying that were the slave states to remain in the Union their slaves would ultimately end up being freed by the anti-slavery Republican Party.

He stated that he would rather be stricken with illness and starvation than see African Americans liberated from slavery and be given equality as citizens: What was the reason that induced Georgia to take the step of secession?

That is the fate which abolition will bring upon the white race.... We will be completely exterminated, and the land will be left in the possession of the blacks, and then it will go back to a wilderness and become another Africa....

I say give me pestilence and famine sooner than that.Although he was considered for a cabinet position in the government of the newly-established Confederacy, he chose to join the Confederate army instead and became the colonel of the 17th Georgia Infantry, a regiment that he raised himself in Columbus on August 29, 1861.

He missed the Confederate victory at the Battle of Chancellorsville because his brigade was stationed in southern Virginia along with the rest of Lieutenant General James Longstreet's First Corps.

There, on July 2, 1863, Benning led his brigade in a furious assault against the Union position in the Devil's Den, driving out the defenders at no small cost to themselves.

On the second day of the bloody Battle of Chickamauga, Benning participated in Longstreet's massive charge against a gap in the Union line even as his horse was shot out from under him.

Riding an old artillery horse and whipping it with a piece of rope, Benning was "greatly excited and the very picture of despair," as was reported by Longstreet after the war.

[6] The Benning's Brigade fought at the Battle of Wauhatchie outside Chattanooga, Tennessee, and joined Longstreet's Corps in its unsuccessful Knoxville Campaign in late 1863.

Returning to Virginia, the brigade fought against Union Lieutenant General Ulysses S. Grant in the 1864 Overland Campaign, where Benning was severely wounded in the left shoulder during the Battle of the Wilderness on May 5.

His brigade withstood strong Union assaults against its entrenchments but was forced to withdraw along with the rest of Lee's army in the retreat to Appomattox Court House in early April 1865.

He found that his house had been burned; all of his savings had disappeared; and he had to support, along with his own family, the widow and children of his wife's brother, who had been killed in the war.

Regarding Mary Benning, Mitchell wrote, "She was a tiny woman, frail and slight, but possessed of unusual endurance and a lion’s heart.

Left in complete charge of a large plantation, this little woman, who was the mother of ten children, was as brave a soldier at home as ever her husband was on the Virginia battlefields.

The SS Henry L. Benning, United States Merchant Marine 0946, was built in Baltimore, Maryland and went into service on March 9, 1943.

In 2020, during the George Floyd protests, there were renewed calls to rename U.S. Army installations named after Confederate soldiers, including Fort Benning.