It was oil firing by this time, yes. Some may remember the credit Winston Churchill received, as First Lord of the Admiralty before WWI, for converting the Royal Navy from coal to oil.
There are some sad stories of men being scalded to death from live steam during enemy attacks, but at the time there was no real option for powering larger ships. The nuclear-powered vessels still use steam turbines today, but destroyers in the US Navy use gas turbines, made by GE I think. They're derived from the engines used on 747s.