 Complete the following phrase:  Rosecrans launched the Chickamauga Campaign in late August, staging demonstrations near Chattanooga and upstream of the city along the Tennessee River. This convinced Bragg that Rosecrans was crossing the river to the north; however, Union forces were actually crossing to the south of the city. This forced Bragg to fall back into northern Georgia, abandoning the important railroad hub of Chattanooga on September 8. Over the course of the next several days, Bragg attempted to launch several attacks on isolated parts of the Union army but each attempt failed. On the evening of September 18, Bragg concentrated the army near Chickamauga Creek; he thought that only part of the Union army was nearby but Rosecrans had concentrated his army faster than Bragg had expected. During September 19 