The Battle of Fort Davidson (The Battle of Pilot Knob)
In September, 1864, General Stirling Price led the Confederate Army of Missouri into Missouri out of Arkansas with the intent of capturing St. Louis. Along the road was Fort Davidson at Pilot Knob, Missouri, in Iron County at the terminus of the St. Louis, Iron Mountain, and Southern Railway Company. The fort was manned by 1500 Union regulars.
Price chose to attack the fort with his army of 12,000 (3000 of his men were unarmed, and the stores of weapons and ammunition were one of Price's reasons to attack).
After a skirmish in Ironton on September 26 (including exchanges of fire in front of the still-standing Iron County Courthouse) the out-numbered Federals withdrew into the fort.
Price began the attack on the fort itself the next morning with four divisions, each attacking from a different direction. However the attacks were not properly coordinated, allowing the fort's heavy guns to be directed against each attack individually. Outnumbered Union troops were driven off Pilot Knob and Shepard's Mountain by superior Confederate forces, however the fort's drymoat and steep walls, and the poorly coordinated attack, prevented Price's troops from seizing the fort. Only one Confederate division successfully reached the fort, but were ultimately driven off by a combination of cannon and musket fire, and hand-grenades pitched over the sides of the earthen walls.
That night Price ordered his men to construct scaling ladders. Union General Thomas Ewing, receiving a late order to abandon the fort, agreed the position was untenable and ordered an evacuation. The Federals muffled the drawbridge to cover their escape. They withdrew northwest--BETWEEN two Confederate encampments--and left a slow fuse burning in the fort's magazine. The fort exploded well after the troops had withdrawn, leaving the fort unusable to Price and denying him the stores on which he had partly based his decision to attack.
Rather than pursue the retreating Federals at the demands of his staff (who were enraged at the deception) Price continued north. He had lost 10% of his force in the engagement. Despite abandoning and scuttling the fort, the Federals successfully delayed Price long enough that St. Louis was removed from danger, as in response to this battle (and a concurrent raid by Bloody Bill Anderson) the city was reinforced.
Ultimately, after a three-month foray across Missouri, parts of Kansas and Indian Territory before retiring to Arkansas Price lost half his army. What was intended as an attempt to officially seize control of Missouri (Missouri was claimed by both sides during the war: in fact there was a civil war WITHIN the Civil War in Missouri, like nothing seen in any other state during the war. Additionally, only Virginia and Tennessee had more battles fought within their borders) and turn public opinion against Lincoln's management of the war ended in failure. Capturing St. Louis would have been a major blow to the Union, as its position made it a key hub in transportation on both the Missouri and Mississippi Rivers, not to mention its importance as a supply base. Losing Missouri would have been a major psychological blow to the Union's efforts in the Western Theater.
As an aside, I had a great-great-great-uncle who served in the 5th Missouri Cavalry (Union) under Pleasanton, who participated in the pursuit of Price.
