World War II question?

I was going through my grandfather Discharge Orders from the Army. He served during WWII. Under Battles and Campaigns it reads " GO 33 & 40 WD 45 RYUKYUS". Can anyone tell me what these stand for? I know he was in the Pacific Theatre for 16 months. He received the Bronze Star while he was there. Unfortunately, I was never able to ask him these questions before he passed away. Can anyone help with these?