Warspite and Somerville at Savo Island

What changes if Warspite and her crew replace HMAS Australia one day before the Battle of Savo Island?

Somerville takes command and Warspite's radar, 15-inch guns, and command facilities make the Japanese cruiser attack far more dangerous.

Replacing HMAS Australia with Warspite brings a battleship whose radar-directed 15-inch guns greatly overmatch the Japanese cruiser force. The accompanying appearance of Admiral Somerville matters as much as the hull, because his seniority clarifies coalition command before the battle begins. At night the Japanese may not identify the battleship until it opens fire, leaving little opportunity to avoid an engagement. The ship would also give Marines powerful shore bombardment, while Australia taking Warspite's place would have a smaller effect on the carrier-centered Operation Stab.