In March 1942 , three months after the Japanese attack on Pearl Harbor and the subsequent American entry into the conflict , he was promoted to the one - star rank of brigadier general and became the Assistant Division Commander ( ADC ) of the 9th Infantry Division .
In March 1942 , three months after the Japanese attack on Pearl Harbor and the subsequent American entry into the conflict , he was promoted to the one - star rank of brigadier general . 
 In July he was promoted to the two - star rank of major general and became Commanding General ( CG ) of the 9th Infantry Division .