What did John write to Nancy about the war?

In June, there is a letter from John. He writes about the battle at Chickamauga. At Chickamauga, the Union Army of the Cumberland had met Bragg and Longstreet. The outnumbered Union army had been defeated. George Thomas, called "The Rock of Chickamauga," had persisted in holding out with his men until the Confederate general, Bragg, gave up to leave Thomas who returned to Chattanooga free. But Rosecrans, McCook, and Crittenden are all criticized for losing control of their men. After Vicksburg and Gettysburg, the battle at Chickamauga is a setback for the North and hard for people to accept.