After a number of searches led me down the sidetrack of Griswold (founder of Griswoldville) and Gunnison, of Griswold and Gunnison revolver fame (arms manufacturers but not brothers, not from England, and didn't die at Savannah), I finally found the subject of the question here:
http://www.findagrave.com/cgi-bin/fg.cgi?page=gr&GRid=153183456
Major Ferdinand William Charles Cook, Sr. and his brother Francis relocated from New Orleans after its capture and ended up in Athens, GA, where they ran the
"COOK & BROTHER CONFEDERATE ARMORY
"To this building in 1862 was brought the machinery of the armory established in New Orleans at the outbreak of the War by Ferdinand W. C. Cook and Francis L. Cook, recent English immigrants, the former a skilled engineer for the manufacture of Enfield rifles, bayonets and cavalry horse shots. Said to be the largest and most efficient private armory in the Confederacy. It produced a rifle declared by an ordinance officer to be "superior to any I have seen in Southern manufacture." Under contract to supply 30,000 rifles to the Confederate Army the armory operated until its employees, organized as a reserve battalion under Major Ferdinand and Captain Francis Cook, were in 1864 called to active duty upon the approach of Sherman's army. The battalion took part in the battles of Griswoldville, Grahamville, Honey Hill, and Savannah where Maj. Cook was killed. "
It's fun finding out about these relatively obscure characters who actually contributed a lot to the war effort.