1. The Battle of Chickamauga began on September 19, 1863, but it was on September 23 that Union General William Rosecrans learned his army had been outflanked by Confederate General Braxton Bragg. This led to a Union retreat and a Confederate victory in one of the bloodiest battles of the Civil War.

2. On September 23, 1955, white men murdered African American teenager Emmett Till in Mississippi, sparking outrage and protests across the country. His death helped galvanize the Civil Rights Movement and is still remembered as a clear example of the violence and racism faced by Black people in the South.

3. In 1889, the first meeting of the Tennessee State Board of Health was held in Nashville on September 23. The board was created to oversee public health initiatives and address issues like infectious diseases, sanitation, and hygiene across the state.

4. The Tennessee Valley Authority (TVA), a federal agency responsible for managing the power grid and water resources across several states including Tennessee, was established on September 23, 1933. The TVA has been credited with transforming the region's economy and improving quality of life through its infrastructure projects.

5. On September 23, 1806, Meriwether Lewis and William Clark returned to Nashville after their famous expedition to explore the American West. The two explorers had been commissioned by President Thomas Jefferson to find a water route to the Pacific Ocean and map the newly acquired Louisiana Territory, and their journey remains a landmark achievement in American history.