He was suspended from his appointment and held under arrest starting November 13, 1861, although his confinement was expanded to the city limits of St. Louis, Missouri after February 22, 1862, in anticipation of a court martial in October 1862.
On January 28, 1863, after being held in arrest for more than a year, McKinstry was cashiered "for neglect and violation of duty to the prejudice of good order and military discipline."
After his dismissal from the Union Army, McKinstry was a speculator and stock broker in New York City, 1864–1867, and land agent in Rolla, Missouri, 1867 – c. 1870, although he spent most of the rest of his life in reduced circumstances in St. Louis.
[6] With help from his father, Justus McKinstry entered the United States Military Academy at West Point, New York on July 1, 1832.
[7] Fearing that he would fail the math exam at the end of the term and be expelled, McKinstry resigned from the Academy in a December 1832 letter and ultimately left on January 31, 1833.
[1][17] Although he was a quartermaster, McKinstry was awarded a brevet appointment as a major in the Regular Army (United States) for gallant and meritorious conduct after taking command of a company of volunteers at the Battles of Contreras and Churubusco, to rank from August 20, 1847.
[1][2][10][17] McKinstry was an original member of the Aztec Club of 1847, which was founded as a military society of officers who served with the United States Army in the Mexican–American War.
[17] During this 30-month period in Florida, McKinstry served as quartermaster under the close control of Brigadier General William S. Harney and Colonel Gustavus Loomis.
[2][17] On July 3, 1861, President Abraham Lincoln appointed Major General John C. Fremont to command the Department of the West, headquartered at St.
[26] Historian Bruce Catton cites McKinstry as performing a great service to the Union cause by introducing Brigadier General Ulysses S. Grant to Fremont.
McKinstry immediately got Fremont's attention and told him that he had observed Grant's gallantry in Mexico and that he was a reliable man for the job.
[1][34] Fremont assigned McKinstry to command Division 5 of the Department of the West between September 24, 1861 and October 24, 1861 as Fremont's army of five divisions, about 30,000 men, moved out toward Springfield, Missouri in an effort to capture the strategically located town from Confederate Missouri State Guard forces under Major General Sterling Price.
[35] Zagonyi's small Union force briefly occupied the town but withdrew because they had lost many of their horses during the fight and the Confederates would have outnumbered them if they had counter-attacked.
"[1] A St. Louis contractor, Child, Pratt & Fox, admitted to making a profit of $280,000 on $800,000 in sales during the few months of McKinstry's command of the quartermaster department at St.
[2] Historian Stewart Sifakis wrote: "While there may well have been other crooks in the uniform of a Union general, New York-born Justus McKinstry was the only one convicted and dismissed during the Civil War.
[32] On January 28, 1863, after more than a year under arrest and three months after his court martial hearings, McKinstry was cashiered "for neglect and violation of duty to the prejudice of good order and military discipline.
[5][40][41] After his dismissal from the Union Army, McKinstry was a speculator, stock broker in New York City, 1864–1867 and land agent in Rolla, Missouri, 1867–1870.