Detailed Instructions: In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.
Problem:Passage: During Sherman's Atlanta Campaign in 1864, his Army Group was composed of the Army of the Tennessee, the Army of the Cumberland, and the Army of the Ohio. After the fall of Atlanta in September, Sherman sent the Army of the Ohio and the IV Corps of the Army of the Cumberland north to deal with the remnants of Lt. Gen. John Bell Hood's Army of Tennessee. Then, in November, he created the Army of Georgia, by combining the remaining XIV Corps and the XX Corps of the Army of the Cumberland. This new army, placed under the command of Maj. Gen. Henry Warner Slocum of the XX Corps, served as one of the two wings in Sherman's March to the Sea. The Army of the Tennessee, consisting of the XV and XVII Corps, commanded by Oliver O. Howard, served as the other wing. The Army of Georgia was involved in little fighting during the March to the Sea but was engaged in the Battle of Averasborough and bore the brunt of fighting at the Battle of Bentonville.
Link Information:

It appears that the term "Army of the Tennessee" was first used within the Union Army in March 1862 Answer: The Army of the Ohio
Solution:
Which of Sherman's Army Groups were the oldest?