 
                                                                                                    10/19/2025
                                            From Boonville to Palmyra: The Tragic Fate of Thomas Allen Sidenor
The Palmyra Massacre of October 18, 1862, remains one of the most infamous events of Missouri’s Civil War—a grim episode of retaliation that sent shockwaves through both sides of the divided state. Though the executions took place in far northeastern Missouri, one of the men shot that day had once fought at Boonville.
Thomas Allen “Tom” Sidenor, born in 1837 in Monroe County, was a young Missourian of strong Southern leanings. In the summer of 1861, he joined Captain Frank Davis’s company of the Missouri State Guard, which soon came under Major John Poindexter’s command. That September, Sidenor rode with his comrades in the Second Battle of Boonville, an attempt to retake the town from Federal control. The engagement on September 13, 1861, centered around the old fairgrounds—a fortified position manned by Union troops. The attack failed, and the State Guard forces withdrew, but the skirmish showed how fiercely both sides vied for control of central Missouri during those first months of war.
Sidenor's actions after Second Boonville and Lexington aren't well known to me at the time of this writing, but he continued to serve as the conflict in Missouri turned increasingly brutal. By 1862, many members of the State Guard had returned to central and North Missouri to act as recruiters for new Confederate troops. Many also doubled as Partisan Rangers, engaging in guerrilla-style warfare. 
He rode with Colonel Joseph C. Porter, whose Confederate recruitment and raids swept across the northeast. After Porter's defeat at Kirksville in early August 1862, Sidenor decided to quit the service and returned to his home in Monroe County. 
While Sidenor hid himself away, Porter raided Palmyra in Mid-September. He released Confederate prisoners, destroyed provost records, and carried away an elderly Unionist named Andrew Allsman - a man who was acccused of informing on Southern sympathizers. Allsman's fate was unknown, but most assumed he had been murdered. 
Back in Monroe County, Tom Sidenor grew concerned about remaining openly at home and decided to seek refuge in Illinois. He attempted to disguise himself - using ladies apparel in some accounts - and traveled with a female cousin, a sister, and his brother Jackson towards Canton. There they intended to cross the Mississippi River into Illinois. 
They passed through Shelbyville on October 1, 1861 where the ladies and Jack Sidenor were recognized and federal pursuit quickly followed the wagon - suspecting that it was taking supplies to Sidenor and his men. Captain Tom Sidenor was discovered and taken into custody by Union troops. He ultimately became one of several prisoners held in Palmyra, Missouri.
The issue of Andrew Allsman now came to figure in a distressing manner for Sidenor. On October 8, 1862 - Brigadier General John McNeil issued an ultimatum to Porter and local guerrillas: Unless Allsman was returned unharmed within ten days, ten prisoners linked to Porter's command - already in Federal custody - would be shot.
Allsman was never returned.
On October 18, 1862, McNeil’s order was carried out. Ten men—among them Thomas Sidenor—were taken from their cells, seated on their own coffins, and shot by firing squad at the fairgrounds just outside Palmyra. Newspapers called it a “terrible execution.” Federal officers justified it as a military necessity; Confederates condemned it as murder. The names of the dead—Willis Baker, Thomas Humston, Morgan Bixler, John McPheeters, Hiram Smith, Herbert Hudson, John Wade, Marion Lair, Eleazer Lake, and Thomas Sidenor—were later engraved on a monument in Palmyra’s cemetery, where most of them rest today.
Sidenor was just twenty-five years old. His remains were later brought home to Monroe County, where he lies in Sidener Cemetery, his stone and official site lost to overgrowth and time.
Though the Palmyra Massacre occurred miles from Boonville, it is deeply connected to our region’s wartime story. One of its victims had once fought in the fields east of town. His death stands as a reminder of how Missouri’s war—so often personal and bitter—reached from one end of the state to the other, claiming lives long after the sound of battle had faded.                                        
 
                                                                                                     
                                                                                                     
                                                                                                     
                                                                                                     
                                                                                                     
                                                                                                     
                                                                                                     
                                         
   
   
   
   
     
   
   
  