Chattannoga Child Mayor Andy Berke should know that both the USA and the CSA during the war had constitutions that enshrined slavery.
And both the USA and CSA had presidents that took oaths to uphold their nations’ pro-slavery constitutions. In fact, the USA’s president - President Lincoln - took the oath twice.
Most Southerners fought because the Yankees were invading their states, their cities and towns and creating mayhem in the process.
I remember reading an old anecdote about a Confederate enlisted man who was captured in Virginia.
The Confederate soldier was sitting on the ground under guard when a Union officer walked up to him and asked the Confederate soldier why he was fighting.
The young Southern soldier raised his head and looked at the Union officer as though the Yankee had two heads.
The Confederate soldier looked the Union officer squarely in the eye and answered, “Because you’re HERE!”