He rose to Brigadier General.
When speaking of a specific incident or time in place, it is customary to refer to someone in the rank that they were at the time.
When he flew the Enola Gay he was a Colonel. You wouldn’t say Brig. General Tibbets dropped the bomb on Hiroshima, you would say Col. Tibbets dropped the bomb....
If you think of Band of Brothers Dick Winters is often referred to as Lieutenant Winters outside the film, when in fact he rose to the rank of Major. During the Battle of the Ardennes, he was a Lieutenant.
Hope that helps.