Union troops under General William Rosecrans defeat a Confederate force commanded by General Sterling Price at Iuka in northern Mississippi. The Battle of Iuka was part of a Confederate attempt to prevent General Ulysses S. Grant from reinforcing General Don Carlos Buell in central Tennessee.
In the fall of 1862, Confederate General Braxton Bragg had invaded Kentucky to prevent the Rebels from losing any more territory in the West. The Confederates hoped to keep Union forces in western Tennessee and northern Mississippi occupied to prevent any transfer of troops to Buell, who had moved north to stop the invasion of Kentucky.
Sterling Price and Earl Van Dorn commanded the two small Confederate armies operating in northern Mississippi, while Ulysses S. Grant led the Union forces in the area. In addition to preventing Yankee reinforcements in Kentucky, the Confederates also hoped to invade western Tennessee. Grant effectively thwarted both of these objectives by sending troops under General William Rosecrans to move on Price's army at Iuka from the south. He also dispatched another force under General Edward Ord to approach Iuka from the west. But poor communication and delays prevented a combined attack, and Price launched a preemptive assault on Rosecrans on September 19.
Despite the intense fighting, Rosecrans was able to hold Price's force at bay. Repeated Confederate attacks resulted in heavy losses for the Rebels: 1,500 of 14,000 troops engaged. Yankee losses amounted to 790 out of 17,000 present. With Ord's force nearby, Price realized he was in danger of being trapped, and so he abandoned Iuka that evening.
Ord may have joined in the battle, but a strange quirk of nature known as an acoustic shadow prevented him from hearing the sounds of battle just a few miles away. Acoustic shadows form when sound is unable to reach certain locations due to atmospheric conditions or terrain features. Although he saw smoke, Ord assumed Rosecrans was burning captured supplies.