Question: James Calhoun was the brother-in-law of a soldier who was brevetted to brigadier general at what age?

Context paragraphs:
Robert Johnson Henderson: Robert Johnson Henderson (November 12, 1822 – February 3, 1891) was a Confederate States Army colonel during the American Civil War (Civil War).  His obituary stated that he was made a brigadier general by General Joseph E. Johnston, after Johnston witnessed Henderson making a desperate charge at the Battle of Bentonville, North Carolina, on March 10, 1865.  At the suggestion of his divisional commanders, Henderson signed his parole as a brigadier general.  Later, Henderson stated in his pardon application that he had been recommended for promotion to brigadier general but had never received a commission.  Henderson commanded a brigade for several weeks at the end of the war but never was officially appointed by Confederate President Jefferson Davis and confirmed by the Confederate States Senate to brigadier general rank.

Bradley Winslow: Bradley Winslow (August 1, 1831 – October 24, 1914) was an American Civil War Union brevet brigadier general.  He enlisted as a lieutenant on May 9, 1861.  He fought in the Second Battle of Bull Run and the Siege of Petersburg.  He was brevetted as brigadier general on April 2, 1865.

George Armstrong Custer: Custer developed a strong reputation during the Civil War.  He participated in the first major engagement, the First Battle of Bull Run on July 21, 1861, near Washington, D.C. His association with several important officers helped his career as did his success as a highly effective cavalry commander.  Custer was brevetted to brigadier general at age 23, less than a week before the Battle of Gettysburg, where he personally led cavalry charges that prevented Confederate cavalry from attacking the Union rear in support of Pickett's Charge.  He was wounded in the Battle of Culpeper Court House in Virginia on September 13, 1863.  In 1864, Custer was awarded another star and brevetted to major general rank.  At the conclusion of the Appomattox Campaign, in which he and his troops played a decisive role, Custer was present at General Robert E. Lee's surrender to General Ulysses S. Grant, on April 9, 1865.

James Calhoun (soldier): James Calhoun (August 24, 1845 – June 25, 1876) was a soldier in the United States Army during the American Civil War and the Black Hills War.  He was the brother-in-law of George Armstrong Custer and was killed along with Custer in the Battle of the Little Bighorn.  His brother-in-law Myles Moylan survived the battle as part of the forces with Major Reno and Captain Benteen.

Lee's Mill Earthworks: Lee's Mill Earthworks is a historic archaeological site located at Newport News, Virginia.  The earthworks formed part of the fortifications along the James River, which included fortifications at Fort Crafford, as well as, Dam No.1, and Wynne's Mill in Newport News Park.  On April 5, 1862, advance units of Union Brigadier General Erasmus D. Keyes' IV Corps, under the command of Union Brigadier General William Farrar Smith, encountered Confederate units commanded by Brigadier General Lafayette McLaws at Lee's Mill.  Heavy rains and massive earthen fortifications defending the river crossing stopped the Union troops from proceeding to Richmond.  Confederate Major General John B. Magruder's extensive defensives beginning at Lee's Mill and extending to Yorktown along the Warwick River caused the Union Army of the Potomac Commander Major General George B. McClellan to initiate a month-long siege of the Warwick-Yorktown Line which lasted until May 3, 1862 and contributed to the eventual failure of McClellan's campaign.

3rd Regiment, Arkansas State Troops: At the beginning of the war, the Arkansas Succession Convention created the Provisional Army of Arkansas.  The Provisional Army was to consist of two divisions: the 1st Division in the western part of the state was to be commanded by Brigadier General Pearce, and the 2nd Division in the eastern half of the state, commanded by Major General James Yell.  The intent of the Secession Convention was to transfer these state troop regiments into Confederate service as quickly as possible, to avoid the cost of paying for a large state army.  The troops of the eastern division were transferred to the command of Brigadier General Hardee in July 1861, but the troops of the western division under Brigadier General Pearce were not transferred to Confederate service before they became engaged in the Battle of Wilson's Creek.

James Vote Bomford: James Vote (Voty) Bomford (October 5, 1811 – February 6, 1892) was a distinguished soldier in the United States military and a Union officer in the Civil War, and retired with the rank of Brigadier General.  He graduated from Norwich University in 1828 and from West Point in 1832, and was a colonel in the 8th United States Infantry.  Bomford was twice wounded in action at Perryville (brevetted colonel) and served in the Mexican-American War.  His father was George Bomford, an inventor and military officer in the United States Army, who invented the Columbiad cannon.  His son, also named George, was expelled but allowed to retire following his involvement in the "Eggnog Riot" at West Point.  George did enter the military and retired as a captain.

Benjamin Hardin Helm: Benjamin Hardin Helm (June 2, 1831 – September 21, 1863) was a Kentucky politician, attorney, Confederate brigadier general, and a brother-in-law of Abraham Lincoln.  He was also the son of Kentucky Governor John L. Helm.  Helm was born in Bardstown, Kentucky.  He attended the Kentucky Military Institute and the West Point Military Academy and then went to study law at the University of Louisville and Harvard University.  He served as a state legislator and the state's attorney in Kentucky.  He also served as the assistant inspector-general for the Kentucky state guard.  Helm was offered the position of Union Army paymaster by his brother-in-law, President Abraham Lincoln, a position which he declined.  Helm felt it was an honor to serve in the Confederate States Army, where he was initially a colonel and later promoted to brigadier general.  Helm commanded the 1st Kentucky Brigade more commonly known as The Orphan Brigade.  He died on the battlefield during the Battle of Chickamauga.  Helm was married to Emilie Todd, the half-sister of Mary Todd Lincoln.

William Harvey Gibson: Brigadier General William Harvey Gibson (May 16, 1821 – November 22, 1894) was a Republican politician from Ohio.  He resigned from the Ohio State Treasurer's office in disgrace and redeemed his reputation in war.  He was brevetted Brigadier General of the Union Army's 49th Ohio Volunteer Infantry during the American Civil War.

Henry J. Madill: Henry J. Madill (born 30 March 1829, Hunterstown, Pennsylvania) was a lawyer and U.S. Army Colonel during the American Civil War.  Madill was privately educated, and was admitted to the bar of Bradford County in 1851.  He was elected major of the 6th Pennsylvania Reserves on June 22, 1861.  On August 30, 1862, he was appointed colonel of the 141st Pennsylvania Infantry.  Madill was brevetted brigadier general December 2, 1864 by presidential order.  He was brevetted major general of volunteers on March 15, 1865.  Madill was wounded three times and had six horses shot from under him.

Supporting paragraphs: James Calhoun (soldier) George Armstrong Custer
Answer: 23