Short answers, pulled from the story.
The Chattanooga campaign was a series of maneuvers and battles in October and November 1863 during the American Civil War. Following the Union defeat at Chickamauga in September 1863, Confederate Gen. Braxton Bragg besieged Maj. Gen. William S. Rosecrans and the Union Army of the Cumberland in Chattanooga, Tennessee, and Maj. Gen. Ulysses S. Grant organized a breakout that ended with the rout of Bragg's army.
The Cracker Line was a supply route opened on October 27-28, 1863, to feed the starving Union garrison in Chattanooga. Brig. Gen. William B. Hazen's brigade floated downriver at night on pontoons, seized Brown's Ferry by 4:40 a.m., and linked up with Maj. Gen. Joseph Hooker's force arriving through Lookout Valley, creating a short and reliable supply corridor from Bridgeport, Alabama.
Maj. Gen. Ulysses S. Grant commanded all Union forces as head of the newly created Military Division of the Mississippi. His principal subordinates were Maj. Gen. George H. Thomas, commanding the Army of the Cumberland; Maj. Gen. William T. Sherman, commanding the Army of the Tennessee; and Maj. Gen. Joseph Hooker, leading forces drawn from the Army of the Potomac.
After seizing the Confederate rifle pits at the base of Missionary Ridge on the 25th of November 1863, Thomas's men came under intense fire from above and had no shelter. Many of these soldiers had been defeated at Chickamauga and had endured months of taunts from newly arrived troops. Without orders to advance further, they continued up the ridge on their own initiative, ultimately routing the Confederate line.
Union casualties totaled 5,824 men, including 753 killed, 4,722 wounded, and 349 missing, out of about 56,000 engaged. Bragg reported 6,667 Confederate casualties, with 361 killed, 2,160 wounded, and 4,146 missing, mostly prisoners, from a force of about 44,000. Grant claimed 6,142 Confederate prisoners.
Bragg's defeat at Chattanooga gave the Union undisputed control of Tennessee and opened a corridor into the Deep South. Chattanooga became the supply and logistics base for Sherman's Atlanta campaign of 1864. Bragg resigned command of the Army of Tennessee on the 1st of December 1863, and Grant's victory led directly to his appointment as commander of all Union armies in March 1864.