At the time of the Battle of Shiloh, Henry Brewer belonged to the "Cherokee Davis Grays", Co. "A", 10th Alabama Battalion, known in the field as Clifton's 4th Alabama Battalion. Records are filed with the 55th Alabama Regiment, but that command didn't exist until almost a year later. If you had the opportunity to ask Henry Brewer about his Confederate service, he would not recognize his company as belonging to that regiment.
Also, for what it's worth, since Clifton's Alabama Battalion belonged to Breckinridge's Reserve Corps at Shiloh, we can guess that it carried a flag similar to the Kentucky regiments of that command.
Having become interested in events leading up to secession in Alabama, let me offer that it came about rather suddenly. Based on election results in Alabama during 1859, it appears that maybe four in five men would have opposed secession at that time. The Harpers Ferry attack in October 1859 had a lot to do with getting men to rethink their Unionist sentiments. The final blow to those hoping to resolve difficulties and restore the Union was Lincoln's call for troops in April 1861. As one Alabama Unionist said afterwards, "There is scarcely a greasy spot of us left."